But that situation is not anywhere near impossible. What's more, the patent system is there to serve a purpose, innovation, even (and especially) for the indie developers. Now, if that purpose is not served, which seems to be the case for software, it's time to lobby for governments to interfere, not to give up on independent entrepreneurship.
But keep in mind, the patent trolling industry can't take all the money, or there wouldn't be any more developers to sue. In this case, the parasite methaphor really is apt - if a parasite completely wipes out the host species, then the parasite goes extinct as well.
So yeah, the situation isn't impossible, because patent trolls need to keep the success rate high enough that new software entrepreneurs are tempted to try.
Right - there's probably nothing to stop a 'tragedy of the commons' occurring, and money is fungible so they can just do something else with it when the cash cow dies.
Both can be true. It really might be unprofitable to be an indie developer (after factoring in the risk and cost of litigation), while simultaneously being clearly 'time to lobby for intervention'.
Also, the risk/reward of lobbying for intervention may be vastly higher than is practical for people who would otherwise be indie developers, so in practice going to work for a large corporation might be the only way to spend your life writing software rather than being a patent reform activist.
The patent system had an important purpose during the industrial revolution, and I believe it still has a place for "hard" innovations that require years or decades of research before becoming marketable.
But for trivial cases like most software patents, it is just something to prop up the established big companies (and keep lawyers fed) at the expense of emerging players.