There are winds at 160km/h, so you can go only for 10 days at the end of May, and prepare yourself 2 months before (to get used to oxygen levels), with expeditions that cost 40-130k.
After the 7600 meters it is called death zone, as there is only 1/3 of the oxygen at the sea levl, and it takes weeks to get used to it. If you went there immediately you would die in half an hour.
The Sherpas, Nepalese who help to climb, do a very dangerous job. Their percentage of deaths 10 times soldiers sent to IRAQ, and do not earn enought money for that.
Even helicopters are struggling over 6500 meters, top Everest can only do it without weight and in perfect weather conditions.
In the death zone they have to use oxygen, but the tank only lasts 4 hours, and they need 12. The Sherpas carry them up in the camps. It is also difficult to eat and sleep.
And to reach the summit there are 200 people a day. People might die because they are too slow to climb.
There is a small passage to reach the top that takes 6 minutes each person.
70% of deaths take place with cheap shipments.
4% of people died so far, although booking online this experience is very easy.
4000 people have climbed Everest so far. Sherpas did that several times (up to 21).