Define strength.
Muscles? Patience? Endurance? Tenacity and grit? Tolerance? Character?
What = weak? Likely everyone has an Achilles heel, and most humans have some adversity in thier lives. Even lives of privilege typically contain challenges.
Beware of platitudes that lead you to dismiss others and feel superior.
I like your thought process. And it does depend on extenuating circumstances, but weak is still weak and I detest weakness. I do not fault a fish for not being able to climb a tree, but when you take all circumstances into consideration and one is constantly lacking I find that detestable, we all gave growth opportunities. There is no excuse for certain behaviors.
*have
Depends on what easy life means. Plenty of kids have enough education and resource to have an easy life (outside, internet, school that believes in science) but may not have a reference for spending large or small amounts of money. Structuring your time after you leave high-school, I have to move out and I don't know how to do tax, find work or apply for dole. Know that even if you were at K-mart or wherever as a teenage job you may be able to be promoted to supervisor etc. You have had an easy life and you have to guide yourself through adulthood.