You lay out basically the situation I found myself in. But I set aside some for a future house down payment (less risk for that chunk), future wedding (less risk for that chunk), and even ignoring that, most advice wouldn't say to stuff the remaining 100% into markets.
So maybe 60% went into markets. With hindsight it oftentimes sounds like a good idea to just drop it all in the market. But life is uncertain and crystal balls are in short supply... you would feel stupid if you made $1mil, put it all in stocks, and life came out of nowhere and took a dump all over you when the markets tanked.
Not saying I'm in a bad position, but its nowhere near "1mil at 10% per year (which is in itself kinda a wild base assumption)".
TLDR: people have a rosy unrealistic view of how this works out.