You can only put earned income into a Roth, you can only put up to 6K per year, and you are only eligible to put anything at all for a given year if your total earned income was below a fairly modest threshold. Roth IRA already has plenty of restrictions. The fact that one man happened to be some combo of smart/lucky to make the modest initial investment turn into billions is definitely not an indication of whether the Roth is problematic. I think the parent may be confused about the exact details of a Roth.

You can rollover to get around contribution limits [1], and the government gets your money now rather than later,

> A Roth IRA rollover (or conversion) shifts money from a traditional IRA or 401(k) into a Roth. You can get around Roth IRA income limits by doing a rollover. You'll owe tax on any amount you convert, and it could be substantial.

Limiting the max amount would reduce near-term government tax revenue. So I don't think it would happen.

[1] https://www.investopedia.com/how-to-do-a-rothira-rollover-47....

Interesting, I thought there was an income limit on rollover as well but apparently that was axed in 2010. In any event Thiel couldn't have used this.

You would disincentivize good investments and reduce GDP as a result.