> What is the probability of those things failing during the time you have the MacBook?

and

> ... you can pay them $50-150/year (depending on model) to take that risk.

These things are related, Apple knows what the failure rate in the field for their hardware is, and they "price in" that failure rate into their AppleCare costs. On my iPad pro, that's $90/year.

That said, it is entirely a 'bet' on your part as to whether or not you're in a position to cover costs of repair/replacement in the event of damage. That depends on a lots of factors and includes how much you can tolerate not having the equipment for a while, Etc.