"Enough" for most people seems to be about 75k-95k USD per year equivalent [1]. We _might_ not have enough resources yet to provide that much for UBI [2] but we can drastically raise the baseline level of happiness of the populace.
The only thing that can work is if technology/automation is advance enough that everybody can live happily without depending on other people at all. That even 'other people' can be replaced by virtual people that indistinguishable from real one.
The problem is if everybody live like this, can it be still called society ?
"And, there was substantial variation across world regions, with satiation occurring later in wealthier regions for life satisfaction," Jebb said. "This could be because evaluations tend to be more influenced by the standards by which individuals compare themselves to other people."
Sure, it's 75k now. Is it guaranteed to stay at 75k? There isn't a universal constant by which you can assert "okay, this level of wealth is, and will always be, enough for everyone".
> We _might_ not have enough resources yet to provide that much for UBI.
[1] https://www.purdue.edu/newsroom/releases/2018/Q1/money-only-...
[2] More and more automation could get us there