You can buy a lot of bikes with 600 million dollars. After paying off my my house, and my parent’s house, and my student loans, and my wife’ student loans, and our car, I’d make a trip to the LEGO store, obviously, and then to a bunch of bike shops.
N+1 is the only mathematical equation that I’ve ever been able to remember. It states that the correct number of bikes to own is always the current number you have (N), plus 1 more. Because, let’s face it, every bike is a different ride, and offers different kinds of fun.
Here’s what I’d probably get. (Disclaimer: subject to change based on shit I remember)
Jamis Renegade Elite (for gravel and commuting)
All City Pony Express (for commuting and errands – front and read racks added)
Surly Karate Monkey 27.5+ (for commuting, gravel, and trails)
Surly Straggler 650b (for commuting, touring, gravel, and around town)
Just off the top of my head….
How about y’all?
yankee.velo.foxtrot 
If I had a pile of money to burn on new bikes I’d straight up fly back to England and get fitted out for a fully custom WyndyMilla carbon fibre road bike, matching time trial bike and also one of their super custom road tandems. That would pad out my garage nicely!
https://www.wyndymilla.com/collections/bikes
Then probably a titanium framed winter/gravel all-rounder too. 🙂
Honestly, I would probably spend it on musical instruments. Because I’m odd. 🙂
Nonsense. As a tromboner from 4th grade through my senior year, being musical is an amazing gift. I also own 3 guitars but I suck at playing all of them.
I own several instruments that I can “play”… but not necessarily “PLAY”. I have 2 guitars, a fiddle, an accordion, harmonica, and other various things. But I also think winning the Powerball would give me the time to practice all of them. 😉