I'd like to offer a different perspective from someone who's started a company, launched it, trademarked and lived to regret it!
1. Consider what happens if you have to rebrand for some reason? You spend all that money trademarking and then you have to spend the money all over again because something happens along the way and your trademark has no value anymore. In my case, we discovered that we had a much bigger audience for our products than we originally modeled and the name of our company and product (and trademark protection) was for a name that men wouldn't ever buy (original products were designed exclusively for women and then the men came calling). We had to rebrand out entire company which cost thousands and then go through all the expense of trademarking again.
2. For most startups, money is scarce and you are going to need every dollar you can find to be able to get your company up and running and pay for your operating expenses. Spending money at this stage on protecting something that currently has little to no value is a waste of money in my opinion because if you don't have enough money to operate and grow your business, your trademark will have no value.
3. Most important, in my opinion, think about how much it's going to cost you to defend that trademark in the event there is an infringement. Do you want to spend your money defending your trademark OR on growing your business.
4. It's easy for people who don't have any "skin in the game" to advise about what to do in this situation and I mean no disrespect by that, but it's YOU that has to write the check for everything your business does and you're on the hook if you fail because you run out of money so you have to make the tough decisions about what you're going to spend your money on because you can't do everything at this stage.
5. Most of the comments pertain to situations where you have value in the company and the brand and trademark and you have growth in the company that makes it worth it to have a trademark because it's something that can be licensed but keep in mind, the only way you get to licensing your trademark is if you have a lot of name recognition that can be leveraged by a bigger company that would benefit from licensing your trademark. So, again, you need to keep your money to grow your business to a point where you have wider name recognition and most important, a lot of revenue. Of course, there is a risk of someone coming along and trademarking your name, but at this early stage, it's highly unlikely because you aren't showing any financial value in the market. Remember, you can ways do it at a later date when it's justified.
6. This is all just my opinion.