1. Idiotic salaries is what ruins sportsmanship. It's all about the money, but the joy of winning a race against the best of the best is removed due to excessive pressure by sponsors, stake holders and team managers who demand results, both during the circus and around the circus.
F1 in my opinion has progressed from the need to have BIG BALLS OF STEEL (so big Iron Man would be jealous) to put your life on the line when you bring one of the fastest cars on the planet to (and sometimes over) its limits, ...to what it's now, the one who can get us (stake holders, sponsors, managers) the most money out of it will get to drive.
F1 isn't as dangerous anymore, and that's a bad thing? And I don't see what correlation sportsmanship has with driver salaries.
2. Yup, they need less budget cause they have less money grabbers. It's more of a pure sport in the same way F1 once was. You needed a good amount of money and possible a manufacturer's backing, but you wouldn't need to sell your soul to the devil.
Budgets by the top teams are dictated by "return on investment". Red Bull, Ferrari and Mercedes are willing to spend what they do because the return is sufficient for them. They'll spend every dollar for that last half tenth until they can't justify it. Likewise Audi's investment is equivalent to what they can justify spending. To imply a dichotomy between the two is disingenuous.
Oh and privateers can't be competitive at LM anymore. Without a big money backer willing to spend 100 million+ a year, you may as well not bother in P1. F1 isn't as romantic as it used to be, but neither are top line sportscars.
3. Rejects... rejects... look at number 1. Those who can't bring in enough money for the team to buy Cuban Sigars with for the managers gets rejected.
Because of escalating costs, small privateers are all but obligated to increase expenditures to stay relevant and be somewhat competitive. With the sponsor market being in poor health, to compensate a budgetary shortfall this necessitates hiring drivers that bring budget in addition to their talents behind the wheel.
Factory LMP1 teams don't do this, but neither do Red Bull, Mercedes, Ferrari or McLaren. It's the privateers that don't have enormous financial backing that hire pay drivers: Sauber, Lotus, Manor, but also Rebellion and ByKolles. Yes, both current LMP1 privateers employ pay drivers (Kraihamer at Rebellion and pretty much the entire Kolles driver carousel).
LMP1 and F1 are birds of a feather in many ways.
4. Assumptions. Top technical minds are everywhere, since most design different cars for different 'jobs'. As an example, here's a single companies involvement in making different types of Toyota race cars...
An assumption, but a safe one I'd say. F1 is still attractive and is by far the most renowned European-based motorsport category. There is plenty of technical talent among all disciplines of motorsport, and I'm sure that the top F1 teams have as good a pick of the cream as anyone.