Make a spreadsheet, add probabilities of how things will work with current IPO timelines (+10yrs), chances of exit at each startup stage, the loss your getting from investing the same amount of cash working at bigco in ETFs, projected career growth, cost of living, etc.
There are other benefits to working at a startup though. For one thing you might end up on a great team. For another there's far less bureaucracy and process that gets in the way of doing things. For yet another, most of the truly "cool" things are done by startups, and your chance of getting a job doing something intellectually rewarding is far greater there (in my estimation at least). Simple fact is, FANGs of the world have some pretty cool teams, but those teams as a rule have no open positions, so pro tip: don't go to Google thinking you'll work on Brain or autonomous cars at any point in your future, unless you're joining those teams directly. Startups do have open positions every imaginable type of work, tech stack, or field.
But yeah, do consider whether money to fun balance is there, and if it's worth it for you.
Only if that's actually what you'd do with the money. If working for a startup means working from home in rural/suburban Oregon and working for bigco means you're living in SF proper the rent and ancillary costs may make dumping the excess cash into the market unlikely or not particularly lucrative.