most would get expended on youthful impulses, few would be maturely ‘spent’ as a closing action to extended investigations & deliberations

whether that would be a ‘waste’ is a harder question to answer

I don’t know what they would wish for but what they ought to wish for is home ownership. (Or a stable partner, the two usually go together)

The greatest single thing anyone could wish for is owning a home. Our system is rigged. Rent usually == mortgage + taxes + insurance

So the renter is paying off the landlords mortgage. At the end of 30 years cash flow neutral (or slightly positive) the landlord has an asset that exceeds most people’s net worth. If the renter could have bought instead they’d be miles ahead. The only reason they don’t is that coming up with 20% down is outside most people’s reach unless they’re thoughtful, clever, or lucky.

Most people are teetering one paycheck to another. How are they going to save a hundred or two hundred thousand? But boy if they can, life gets different.

All the temporary or uncertain or impractical wishes are discarded because of your constraint. One satisfying wish would be when adults recognize that some 15 year olds do not have and likely never will have any interpersonal skills or emotional intelligence that the adults then push the kid up against the wall and tell the kid that this person standing next to them is their new life coach, that the kid is to tell this coach everyting they are thinking and/or about to do or not do and the coach will tell them whether to do that or modify that or never ever do that for the following reasons... The kid needs to do exactly what the coach tells them to do. And the kid needs to find themself a part time job because they are going to be paying for that coach now and for the rest of their life. For some people reading this, try to imagine how different our lives would have been if we had been put in the hands of a really really highly skilled coach when we were 15. I think lots more people really need expert coaches than have them.