What I find more interesting is the idea that there would ever be an age limit for a visa (other than children). What could possible be the incentive to exclude people in their 40's and 50's, who likely have more money to spend then someone in their 20's?

For regular work visas, the idea is to attract labor force that will be able to work a full career. In many places retirement terms are fairly generous and I’m guessing a lower level foreign employee who only worked the minimum years could be a net negative to the system.

They can do proof of stake, where some kind of wealth is directly or indirectly demonstrated.

For example, the Cayman Islands had a pandemic program that required staying at certain bubble properties, which were like $10,000 per interval. Not sure what the interval was, but it was expensive and would accomplish the gatekeeping.

Money to spend, they care less than having young, cheap-enough, able to make children, might go back home easily in case of trouble immigrants.

I immigrated in my current country at 26 and it was really easy and warm, and they did everything to quadruple my salary from the european country I came from.

Now that I'm close to permanent residency and 33, I'm thinking of jumping again, but with a kid, an giganormous salary and a lot of money to be picky, I expect to be more a burden for the next country than an obvious cheap asset.

care to share it, I would love to look at that site?

It was https://nomadvisa.io/