The company is doing the work to earn that money.
Nobody would call it "milking" money if they were a billionaire owned company rapaciously leveraging their trapped customers for every dime. I don't think its the right word to use here.
The product will get less bad for me when chasing revenue from me than how bad it will get for me when it's chasing revenue from someone who isn't me.
I'd like to name this as a fallacy - begging the question. The product will be better chasing revenue from you because it will be worse chasing revenue from someone else.
Every company has the option of chasing extra revenue from customers. This company has no other options. Perhaps this makes them better as a company and want to develop a better product so that people naturally want to use it more. Or perhaps they, like so many companies before them, try to see how much they can milk out of their userbase before they lose it.
They also aren't immune to costs around them. If their office rent goes up, or power for their servers costs more, they have limited options. Reduce wages (unlikely), do less good, or get more from users.
I said the product will be better for me. I generally believe that things are better for me when they're trying to entice me versus when they're trying to entice someone who isn't me, but we can debate that, if you want.
In Ecosia's case it's different I think - without accounts and nothing keeping you there, every customer today is a customer that needs enticing again tomorrow.
They were very aware they were herding people like cattle into digital conclaves where they could be milked.
Strangers with candy are great for everyone, until...