Good thing they had the participants complete a time journal so we can see that it mostly went towards leisure time and socializing. Again, I'm not making a moral judgement here - for a similar amount of money relative to my salary I would also shift towards more leisure at the margin.
> I don’t think I’d draw a lot of conclusions
The point of the experiment is precisely so we can draw generalizable conclusions about how money around this quantity impacts people's behaviors/incentives. Many welfare programs offer similar quantities of saving.
I think your reasoning is a bit motivated - this is a pretty good social science experiment that was very careful to preregister their analysis.