Most people with SLRs don't get another lens to complement/replace the kit lens.
sorry but if this argumentation would hold it´s water then any lens beside a kit lens makes no sense for canon.
and canon would not have sold... how many... 90 million EF lenses?
Actually, I know quite a few people who own DSLRs. They only use the 18-55. Canon can sell 90 million EF lenses because pros and serious hobbyists (of which there are many millions) will usually buy dozens of lenses. For all the photographers who don't buy new lenses, there is another photographer who buys many. Canon only needs 9 million customers worldwide to buy 10 lenses each to reach 90 million lenses sold. They have far more customers than that in total...
people are buying a 85mm f1.2 for 1900 euro, so why not a 600mm f5.6 for 2100 euro?
You assume a 600/5.6 would only cost $2200. As I mentioned in my previous post...if one aims to maintain the same level of IQ, that means tightening tolerances, and that's where costs rapidly start to rise. A 600/5.6 could easily cost $4000, and a 600/5.6 that is optically superior enough to warrant that level of cost could easily skyrocket to around $7000. Once you get above the $2500 price point, you really have to justify the cost to a customer. You also greatly reduce your pool of potential customers who can actually afford such cost, meaning the lens has to be that much better. A $2200 estimate is the rock bottom estimate possible...and such a lens probably wouldn't be as good as the 150-600/6.3.
Over that $2500 price point, and you enter a wholly different market, which dictates an entirely different approach, and changes the name of the game. Your asking customers to spend many thousands of dollars, and they will expect a return for every single penny they spend. Your in a cost bracket now where people would probably rather spend more for 600/4 than not. Whether its $5000, $7000 or $12000, gaining a third of a stop additional light isn't really enough...even if the optical quality is great. There has to be more
for that kind of expenditure. (I speak from experience, as I am one of those customers...I own the EF 600mm f/4 L II, I bought it brand new with cash...and the aperture is really necessary
to justify that kind of cost.)
there are enough birders and wildlife shooters out there.
maybe not as much as shallow depth of field portrait shooter.... but still enough i think.
There are certainly lots of them. But not necessarily that many of them willing to spend more than a couple grand. If your in the 7D/100-400mm lens bracket, then your in the cost-savings bracket, not the "I'll spend the dough if you give me the closest thing to perfection money can buy" bracket.