Even if the original founders have the best intentions, large equity up front is unlikely to give you a big payday.
Since, in the traditional VC model the drive is to move toward bigger rounds (A, B, C, etc) and investors get paid back first.
So even if you do start with 10%, you'll probably only end up with a low % percent after 3-4 rounds.
The important thing to note is that this whole thing bamboozles our brains because of unicorn survivor bias. We feel like unicorns and $100m dollar companies are the norm but nothing could be further from the truth.
The chance of being part of unicorn is about 0.006% last I checked. The chance of being part of a $100m+ company is in low single digits (of all startups).
If it ends up just making a few million revenue investors will drop it (because not 10x enough) and you're 2-3% will be worth very little.
If ends up stagnating at $5m for a few years investors will drop it (because not 10x enough).
The overwhelmingly most likely outcome of you getting a large chunk like 10% up front is, when all is said and done, after 5-7 years you'll walk away with a few hundred thousand (before tax) if you are lucky.
In my case I was on founding team. Started out with 10% equity. Co. is now 7 years old. After a merger (diluted by 40%), $10m investment (diluted more), $4m strategic investment (diluted more), then investors taking money off the table first for an exit event - I stand to make $100k if we sell at $20m and $600k if we sell at $40m (currently valued at $20mish and has been for 2 years). That's pre tax.