Yes, it's definitely a numbers game.

It's also an attempt to take a shortcut, and those usually don't work very well. The fact that your buddy has luck with it can be down to all kinds of things, hard to say why it works for him and not for you.

But here's what I would do, IF I'd try cold emailing:

Use it as a way to start a conversation, not as an attempt to get a sale. I'd never ever buy something from someone who tries to sell me something before he even asks me if I'm interested.

Because if he doesn't ask about MY interest, the logical conclusion is that the sale is only in HIS interest, and then the door closes. In other words: cold emailing with an offer is an instant and massive trust-breaker.

Imagine you meet a nice girl... do you walk up to her and tell her to kiss you? Of course not. You'd get kicked in the face. But if you have a chat, hang out with her, go to the movies, spend time and have fun... it might just turn out she digs you. Customer relationships are no different.

So focus on opening a conversation and building the relationship.