If the majority loses sight of the fact that someone has to pay for government entitlement programs, there will not be any way to oppose politicians who say, "Spend more!" Is this what you're trying to say, Werewolf?
There's nothing there that disparages people from actually voting. The argument is that there is some point, we don't absolutely know for sure where, at which a progressive income tax scheme becomes so top-heavy that resistance to increased government spending becomes enough of a minority that government spending will increase unchecked, resulting in a collapse. Either overspending results (eventually) in moneyprinting and hyperinflation, or enough "producers" decide to stop/slow producing that shortages occur. Either results in significant loss of quality of life, which, under certain circumstances, only serves to tighten the noose.
The point at which a majority of the populace no longer pays income tax seems to be an estimate of that point. It's probably a bit higher than that, as those paying taxes probably are somewhat more motivated to vote against spending than those who do not pay are to vote for spending.
However, the fact is that, assuming the prediction is valid, increasing the number of people who pay no income tax brings us closer to the "line," wherever it is. This may (hypothetically) result in a positive feedback loop, pushing the tax structure even further.
I had a conversation with a self-professed progressive a while ago. We talked about progressive income tax. I made the point that (numbers approximate) 15% of the people pay 99% of the taxes, or whatever. He was for increasing the "progressiveness" of the tax. I asked when it would be enough--that is, when x% pays 99% (x<15), it's enough--and he basically said it was irrelevant how top-heavy the system got.
I couldn't really follow the argument as to why he thought it irrelevant. He claimed to want Rawlsian "fairness" for everyone, but there are a lot of problems with that already.
Sorry for the long post.