It depends on the individual but I think you are right to be concerned op.
I think it’s fine if the recipients truly do “work really hard” and are self-disciplined and clear-minded enough to pursue an interest or craft very seriously, but the two individuals I know who live off trust funds do not, and I think their comfortable financial situation has been detrimental to their characters.
The difference between doing a job … or anything really … because you have to and doing it for pleasure … is chalk and cheese.
If you have the security of a trust fund behind you, you never actually have to complete anything, work hard for those exams, inconvenience yourself by doing an extra course of study, go on that work trip that you dreaded but turned out ok, take that job that means you have to get up two hours earlier than normal and commute, put up with individuals who you find extremely irritating, put your bosses demands before your own and so on … .
If you are not careful, all the choices you ultimately get to make are comfortable ones and that over time has an enfeebling rather than broadening effect on your character.
Plus if it is your elders who still hold the key to the vault of the family trust, then it is possible that you remain locked in to a highly problematic relationship with your parents or parent, where they still have ultimate control of you and your major life decisions, at an age when you should long ago have become independent, and this tends to breed resentment and frustration on both sides.
To my mind anyway, trust funds come with a huge price to pay!