Originally Posted by Spock
However, the effort needed to cultivate said friendships is so high that I cannot really have more than one or two best friends.
If having a good friend is an effort for you, then I totally understand that you need to make sure you don't have too many of them. If you do, you'll run out of energy.
There are people who find that having friends is no effort at all, that it in fact it gives them energy. So the problem is not about running out of energy, it's more about managing time and resources.
It probably all comes down to how you relate to other people.