How can an ambitious entrepreneur succeed without the support of a capable team/staff?

You must be doing something right if you’re able to buy this partner out. That’s good you’re in that position.
Now, save yourself some future agitation by deliberately determining what you need in a partner. Take the following steps:
1. Determine what the business needs to succeed (money, marketing/sales, operations/services, etc.)
2. Honestly consider what you do best and what you like to do (not necessarily the same thing)
3. Honestly consider your shortcomings and those things you detest (again, not necessarily the same thing)
4. Use that shortcomings/detest list as your starting point for identifying criteria for a partner
Another route would be to step back even further and ask yourself if you truly need a partner right now. Can you work solo for 6-18 months and get your own traction with some clients? That experience will likely further underscore what duties might be better handled by someone else.

I've gone through this exact experience 2 times. It can be hard to figure out if someone is going to do everything they say they will if you haven't already worked with them.

One of the most important skills an entrepreneur can learn is how to pick amazing people to join them. Otherwise a company will be mediocre like most out there.

It's really hard to build a company on your own. I've done it a few times now and I would advise you to be open to others helping you. It makes the road much easier and more fun. There are plenty of trustworthy, hardworking people out there. You just need to understand how to find them and set expectations.

If someone is interested in working with you, start with a trial period to test them out before getting far into an equity split (assuming you don't have the capital to pay a salary).

Can you presale any customers to get funds?

If it's a employee, they need to vest over time. 4 years is typical. This protects you if they don't work out.

Let me know if you'd like to talk through this more.

Honestly, you most likely can't succeed without the support of a capable team/staff.

Or you can...and did...But that's it. You can be a very small business or a consultant/freelancer. Just like you did.

What was not successful about that for you? How do you define success?

You will ultimately need to rely on others if you want to scale a business. From what I'm reading here though it's not so much the "team/staff" as it is your co-founder. One person in particular?

I don't want to discourage you in any way of course, but realizing you need a team took me a while to figure out myself. Save yourself some time. You'll need to start pushing yourself outside your comfort zone a bit perhaps. You will need to become a bit more social. Start networking (many sites, events and meetups to do this) and look for people to help you without giving away the farm.

Take time to get to know the people and their skillset. Given your co-founder was a classmate, it sounds more emotional than analytical. It's easier to be analytical with complete strangers. Though again, I understand this may push you outside your comfort zone.

By setting expectations up front with new people, I think you'll then find that the people you meet won't be so much of an anchor as they will be a sail.

I chose the wrong partners a few times early in my career. The first step to fix this trend for me was to understand why I was picking the wrong partners. I realized it came down to my own inability to trust myself and what I was capable of accomplishing.

That's not to say I can do it all myself. I've also come to appreciate the importance of connection more than ever. This might seem like a paradox. Let me try and explain how this worked for me.

Early in my career I felt smart and capable. I was also afraid of trusting myself and my ability. This caused me to suppress my true qualities. This led me to selling myself short.

I felt the need to rely on the wrong people for the wrong things. In one extreme example, a board member of a company I was founding suggested I become the CEO, rather than the COO.

I told him all the reasons why I thought my co-founder would make a better CEO than me. The results were somewhat disastrous. We burned through a lot of money, really fast and the company folded. I still hold myself accountable for not stepping up and doing what I was capable of doing as CEO.

I've learned a lot since then. I've learned to trust myself. I've learned to recognize my strengths and weaknesses. I was always good at identifying weaknesses. Learning to address my strengths took time.

Why?

Because once you identify your strengths, it's necessary to act on, not suppress them. Learning to deal with my fear of embracing my own potential has helped me act on my strengths and not suppress them.

I'm not so quick to rely on others now. At the same time, I consciously seek out partners who have skills that complement mine. I also look for partners who share similar values. Finding the value match can be harder than finding the skills complement.

Finding the right match takes time. I'm more patient now, too. I used to favor progress and speed over everything else. This also led to choosing the wrong partner. Now I'm mindful of taking more time than may be initially comfortable to finding the right partner. Rediscovering the power of openness and connection helps me meet more potential partners.

Taking a more deliberate approach means saying no to people and opportunities. That means opportunities may take a little while to manifest. I'm convinced this investment in patience now will pay off in the long run.

Finding the right partner will increase your chances of becoming successful. It will help you enjoy the journey toward success too.

Best of luck on your search. I'd be happy to dig deeper into this with you on a call. My hope would be to help you avoid the mistakes I made and benefit from the discoveries too!