I was lucky enough to cash out of a startup after 7 years and 3 or 4 rounds of funding (I had left by the time I got the payout) as a share buyback for one of the VC investors.
I was diluted from 3.2% to about 1.3% but the value of the company had clearly risen so _at that point_ it was unimportant.
However in my opinion the company's burn rate and lack of growth clearly meant a later exit (likely an acqui-hire IMO) would have seen dilution without an equivalent growth in value, not to mention the ever-increasing VC non-dilution shares accelerating that.
I got majorly screwed on tax because the startup made no efforts to be efficient and were very chaotic in their arrangements for payout so that is definitely another important factor.
Overall by winning the startup share lottery I made roughly $500k for 5 or so years working there and that was as employee #1 so the maths given the pay cut probably don't work out too well (perhaps break even if I'd played the career game well).
However of course I am hugely grateful it happened and I got to see a startup grow from 3 people to more than 10x that and learnt a lot, as well as changing my coding career direction substantially.
I wouldn't recommend joining a startup as a non-founder other than for changing career or starting out. The trade-offs don't really make sense in most cases and you get a lot less say than you think you might (founders understandably want to control what is their baby) - never do it for the money.
note: I posted a more detailed overview of what happened at https://news.ycombinator.com/item?id=25496667