Not single-fund, you can't be that lazy. No such thing as easy money, you have to do your research and be active with your money. Just like old '60s broken jalopy you find in garages. It's depreciating asset, get rid of it and it's much more useful as cash. Same thing with anywhere you park your money. Key is education and learning new strategies that fit modern market.
Investment mentality of masses is still stuck in '60s. Regulatory-changes in 1986 provides A LOT more flexibility and opens up HUGE opportunities in new and novel strategies. Look at both sides of GME/AMC debacle and you'll see awesome new weapons being deployed that simply wasn't possible in the '60s.
Anyway, I must be getting old as I'm pushing conservative strategies with tax-benefits. Never would've even looked at those years ago. Ok, so roth-IRA is nice. Using CAN-SLIM method from O'neil @ IBD, you can do quite well. I started roth-IRA last year since I was maxed-out in roth-401k. I'm up about +93% for 2020. Most people's magical 10% done in single day.
Adding some contributions for 2021, lowers it to +65%, and I still have 11-months to go.