Not everyone is going to share this altruistic approach to running a business. The majority of monetization probably does, plain and simply, come down to greed. But outside of that, you have ambitious people who envision so much more than what they currently offer—which may require large scale growth.
Regardless, I'm sure the majority of people's morality will be skewed when the service you offer grows to 430+ million active monthly users [0].
Each user goes from being an individual to just a single part of this mass-collective, where the difference between making $1 and $2 off each user is so mind-boggling high that it's hard to keep morals in check.
I guess there's a reason sociopaths do so well in business.
[0] https://redditblog.com/2019/12/04/reddits-2019-year-in-revie...
The defense against sociopaths is eternal vigilence.
Funding is needed, monetization at all costs is not.