Link to a CNBC page for people who have done it. I don’t feel $1 - $1.3 million is enough for a couple, especially starting retirement in their 30’s and 40’s (even not considering health insurance), but they feel it’s enough.

https://www.cnbc.com/2018/03/28/steve-adcock-this-surprised-me-most-about-early-retirement.html

I made a $10 purchase of bitcoin as a test. The $10 got me 0.00119335 bitcoin at about $8,379. I checked the current price on Coinbase at as close to the same time as this transaction, at it was $8,343. While they say there is no transaction fee, it looks like they take a bit of a spread.

I probably won’t be doing much, if any, crypto stuff on Robinhood, but it’s nice that’s it’s available.