> Other than 40% federal estate tax and 20% Washington state tax, which is right next to zero.

Took me 5 seconds to Google this:

https://smartasset.com/taxes/5-ways-the-rich-can-avoid-the-e...

Those can wind up deferring taxes, not eliminating them, and still they have exemption limits. The Roth IRA has contribution limits.

Gifts eliminate estate tax up to $12m. You can exceed even that limit by purchasing a property and placing it in a QPRT.

Life insurance trusts also have no limit.

Finally, even if it were true that it's merely deferring taxes, that means you can essentially time the market to pay less in tax when the rules are more favourable, and you can realize more gains in the interim.

Except there are abuses of Roth IRAs and other cases where tax can be completely avoided. I think it was only recent that some limitations of Roth IRAs were put in place for heirs, but such investment vehicles do exist that do not get hit by the normal estate taxation processes.

Roth IRAs have contribution limits.