$100 each for 330 million Americans sums to $33 billion, which is about half of Amazon's yearly profit (the whole company, not just e-commerce). While I think it should be higher still (anti-competitive practices should be harshly punished), it's not negligible. The real point isn't in the consumer payout, but in discouraging these practices, so that a handful of companies don't get a chokehold on the market (one could argue it's a bit late for that...)

It should be 10% gross over the time period covered in the case (or about $65 billion per year)

What percentage of affected users typically enroll in a class action lawsuit? I could believe anything from 1-90%.