Some stay with you, stay friendly with you when things are going good, when you are in good spot, good state in life.
When things get tough, when you are down in life, they (those people) disappear. They are not as friendly, they are not in touch.
These folks are Summer friends - friends only when things are good.
But then,
there are all-weather friends.
They tend to stay with you with ups and downs, stay when things are good, bad and ugly. Be there when you need them the most.
The all-weather friends typically expect nothing in return. Their friendship is not transactional.
Cherish them. Cherish their relationship. Keep them close.