How to invest 500k and maybe retire

[Arthur Means]

Hey all,

I have a cryptocurrency investment that has matured nicely. I am thinking about an exit strategy.  I have a full time job and don't really want to self manage so any real estate would need to be fully managed and I'd basically just be collecting an annuity, if you will. 

I'm 38 years old making roughly 250k per year. I'm thinking about one thing. Retirement (seriously). But I can't seem to make the numbers make sense. 

option 1 - 500k into a mutual fund earning 8% generates about 40k a year. Not bad but not retirement level money

option 2 - single rental, no mortgage maybe makes $3000 per month or roughly the same as option 1.  

option 3 - OPM. 30k each down payment on 15 doors (section 8 maybe?).  Even at $200 per door I still make the same $3000 a month. I feel like I should be able to make more though.  I would also have 15 assets. This feels like I could retire quickly if I did some basic things right. Ultimately id like to make 10k per month but I could live on less. Can someone help with real world numbers for how I should invest this money and leverage it to maximize my return?