It's not their fault in the sense that they all employ deceptive practices to reap a large profit. Certainly, if there is very little competition in that market or if the market has very large barriers to entry, then they can get away with obscene profits. But, yes, in the strictest sense - if they provide a service or product that lends itself to an unreasonably large profit, it means that the true value of that particular good or service is not being produced for consumers.
This leads to the natural repercussion of a widening gap of wealth distribution. No one is saying that there should be a small or medium sized gap. But when you have no consumers left to buy products or services, the whole system collapses.
It depends on the industry and the product.
We would have to start with services that begin at obscene markups - like at 90% or so - and of course, we would have to look at the unit cost of that product/service as well.
I don't know really what to say... You are applying a subjective analysis of what profit levels are acceptable, nor are you recognizing the risk factors or the motivation for people to invest, build, etc.
A reasonable tax rate will not have any negative effect on the business. Certainly if the profit margin covers that tax rate, there would be no effect at all.
This comment deserves special attention:
You do understand that via the 3 levels of taxation (Fed, prov and muni), gvt (ie society) is a substantial partner in your business.That said, by limiting the profit capability of corps and individuals, you limit the tax revenues for everyone.