Here is from the flattr site:
"On incoming revenue you keep 90%. When you add money to give to others or withdraw money you earned you only pay a fee to the payment provider you choose."
So, they charge 10%. Paypal doesn't even charge you anything close to this. I also like how they tried to make it sound like it's not that bad, by talking about how much you actually get to keep rather than the fee itself.
I guess you need to make a profit/pay for server/infrastructure costs...so do artists, movie makers, and software developers.
It's so easy to take the hard work of others and in most cases, against the wishes of the original content creator, and just give it out for free. Anybody can buy a couple of servers, index a bunch of content, and put it up in a foreign country.
TPB isn't fighting for your freedom. They are helping in the demise of independent artists. Sure, you will always have a few people that play for free because it's fun, but because of the current state of the Internet (the new generation feels like they are entitled to music and anything else online, for free), it's going to be very difficult to actually make a living unless you are signed to a major label.