Why is it possible for only for a few massive stars to have great ends, like forming a black hole?

Small stars like the sun are content to quietly swell up to be red giants then slowly shrink down to be a white dwarf. They don't have enough mass to make a supernova or a black hole.

Small stars are the best hope for the next trillion years. Eventually, their baryons will decay.

Gravity. Less mass means less gravity and it requires massive amounts of gravity to form a black whole.