I believe pro-rata rights are rights to invest in further rounds. They can keep their percent ownership only if they contribute more money. This is like employe

I believe pro-rata rights are rights to invest in further rounds. They can keep their percent ownership only if they contribute more money. This is like employees on vesting schedules, who can continue to get more options by continuing to work. Startup shares are a shitty deal, but this doesn't strike me as one of the reasons.