"I do not belong to any high-risk-group and never had a flu shot in my life so far."
"Quarantine me if I get sick, and that's the end of that, no harm done."
no, no, no, no, no.
There are those who have to take immuno suppressants, or have their immune system supressed, they are at high risk of dying if they catch it. Even if you're going to survive catching it, unless everyone gets the vaccine (~75%) there's no point, as you said the healthy people will survive.
"this is a way of population control to WHO who are saying this is a must for all population." - yes it is population control, they are specificallytrying to keep as many people alive and healthy as posisble by stopping this virus from spreading. If they were trying to cull the herd (those wea in our over-populated world) then they would just not deploy the vaccine.
I don't know what testing has been done. The media tends to get all hyped up because historical medical evidence indicates a large flu outbreak every ~80 years, and given that the last one was 1918 this one is overdue. (that is a mutation which causes the flu virus to spread and kill more people) Ask any statitician and they may tell you that there is the same chance of a flu epidemic this year as there have been any other year...
of course i imagine that flu pandemic in 1918 would have dramatically increased flu immunity in the population (those who survived) and thus decreased the chances of flu finding carriers to spread it in the next year. (and this immuniy has been dropping off ever since) However the travel habits, and exposure to other people has changed greatly in the past century, so you would expect virus mutation and spreading rates to be greatly altered - i imagine more humans to incubate the virus, and more of them travelling around the world to spread it would increase the chances of a particularily dangerous version(but i'm no expert) - that said regular vacination of the population may have the effect of decreasing the number of humans who are incubating the virus, and who are carriers.
i don't know anyhting about vaccine creation and testing (other than the fact that they use eggs to grow the virus, possibly chicken eggs, and to create the vaccine)