I worked my ass off to reach financial independence, now I'm dedicating the rest of my life towards helping other people.
I've proven to be capable of using the system to a degree where I can do whatever I want, which allows me the freedom to help other people full time.
It's not a perfect system, but I doubt UBI will be much better. At least capitalism filters out many of the people who shouldn't be helping others.
Helping those in need isn't something everyone should be doing. Not every needy person should be helped and helping others in desperate need incurs a mental cost that's not easy to carry.
But in my opinion, in today's society, if you take away the need for people to struggle (which UBI will do) they often end up in a worse mental and physical shape than if you make them suffer a bit. Just the way natural selection programmed us. "All basic needs are met <- conserve energy".
I can imagine a educational system where we prepare our children from childhood for UBI and it will work.
But given how rudimentary most education still is I don't see that happen anytime soon. Maybe in 100 years.