Every living organism that doesn't have photosynthesis may be seen in some way as a parasite.

Every individual live in something like an ecosystem. I would argue that society is part of the ecosystem for humans.

Whether or not (or in what cases) one individual should be forced to give up resources to another will be a never-ending discussion. Should government money be used for development aid abroad? For social welfare domestically? Are you responsible for caring for your parents? Your sibling? Your children? Is a mother responsible for providing her biological resources to an unborn child?

We may never come to permanent, full agreement on most of these questions.

"in some way" sure, but in lots of other ways not. For the sake of discussion let's pose one way in which we could define the distinction as a purely utilitarian metric - does an individual contribute more to society than they take out. The problem is that it seems to me that many individuals are professionally parasitic. That is their jobs, which they carry out diligently and conscientiously, don't contribute anything useful. As such they are purely drains on society.

I would put much of the finance industry in that bracket, which is essentially a rent seeking industry (albeit in various convoluted ways). It's doubly bad in finance because it sucks huge amounts of talent from areas where the individuals could actually contribute usefully.