The need to work already stifles people's success. People spend time working "dead-end jobs" where every hour worked diminishes their chance of future success.
If people didn't have to work that _______ job, they wouldn't. But they do, because they have no choice.
A basic income gives them that choice. It does not "stifle" it.
I'm not sure how that's a "crutch."
Also, in the future utopia you're describing where no one has to work a shit job that "stifles [future] success"... who cleans the toilets? Who waits tables?
I personally believe basic income is a much better solution than the wellfare systems we have in place to deal with mass unemployment. Traditional need-based wellfare systems actually disincentivize work in that you can often lose wellfare benefits once you start working full-time, whereas basic income has no strings attached, and any work you choose to in hopes of improving your standards of living will actually improve your standards of living instead of being a trade-off.
The robots, of course.
I mean, the reason why this is an issue in the first place is due to rapidly increasing advancements in automating people out of the job pool.
Anyone who looks at the current state of self-driving cars and deep learning (ala AlphaGo) and doesn't recognize we are right on the cusp of a huge sea-change in how many jobs we can automate out of existence (at least in the sense that they won't be done by humans anymore) isn't thinking very hard.
And we are currently so far away from useful solutions to this economic problem that we really need to start seriously considering it right NOW.
This may lead to a family-centric economy, where businesses like the city corner-store flourish because the family owns and cares for the business. The economic benefit to the family in aggregate is greater than the basic incomes afforded to the individual family members.
(Also, edited my comment to remove the reference to crutch.)
It's being stuck spending huge numbers of hours on those dead-end jobs that stifles success.
There will be plenty of people that choose to work whatever basic job for a period of time, and leave it later. There will be plenty of people that would take up such a job part-time so that it doesn't stifle them.
In the worst case, you can always pay a good wage.
You can still clean toilets and wait tables to make extra income so you can afford the nice things you may like but aren't needed to live, such as vacations.
If you stopped cleaning toilets you don't starve. That's the idea anyway. You don't have to clean toilets but that is an option if you want to earn some extra spending money.
Not everyone considers cleaning toilets beneath them. I didn't mind having a job where I cleaned toilets, that sort of work doesnt bother me - it's only the pay that is terrible.