The original grant plus all the refreshers would have originally amounted to ~$8M (I was within the first 3 employees), but joining early means that at each and every single round you'll be massively diluted (20%+, and there are many of those from a seed round up to a series D/E), and this is without counting the liquidation preference (which in my case was a good 1X non-participating) and other stuff (e.g. emitting new shares for the newly hired fancy CEO that will help us sell the company, refreshers will have a higher cost basis, ...).

If you join early, expect your relative slice of the pie to shrink by roughly an order of magnitude. In the best case.