The two founders will each own between 3% and 4% of Lyft after the IPO (so $600m to $800m at a $20b market cap). Recode pegged the number at a combined ~7%. Even in a bad scenario in which the Lyft stock dumps in the 6-12 months post IPO, the founders will be very wealthy (consider that its value could collapse to $3.5b and their stakes are still worth roughly $100m each).

More interestingly, despite the relatively small ownership stake they nearly majority vote control Lyft through dual-class shares with a very unusual 20 to 1 vote ratio versus the normal shares.

Even owning 1% of a $15B company still makes you worth $150 million.

Dumping even 2% of that $150M would give you enough to retire.