The more people start using it the less volatile the price will become.
How can you be sure of that ? Are there any argument to prove it?
Take the example of currencies like USD or Euro. There are 100 millions people who use them and yet there is need for a central bank to make the regulation.
And does the central bank with all these regulations stop inflation? No. It's in the nature of currency to be volatile, we just need to get to the point where it becomes stable enough for everyday use. There are also altcoins out there that try to battle volatility by adjusting the supply or attempting to attach them to IRL resources and so far these attempts haven't been very successful.
- Why is it still impossible for me to pay with bitcoin in 99,99% of supermarkets, restaurants, gas stations
Because not all merchants have adopted it yet. Just 2 years ago the idea that so many mainstream business would start accepting bitcoin was viewed by a lot of people as insane, so give it some time. There's still a long road ahead.
I agree with you. But why not be more proactive : What does the community do to make it easier for businesses to have a payment terminal for bitcoin for exemple.
There's plenty of material out there to help business owners that are new to bitcoin
https://en.bitcoin.it/wiki/How_to_accept_Bitcoin,_for_small_businesses- Make concessions to meet certain laws
What laws?
Anti-Money Laundering (AML) and Know Your Client (KYC) measures
The Bitcoin protocol has no concept of money laundering or people's identities, it's an equal playing field for everyone. I don't believe the design should change unless the majority of community demanded it. So it should be up to the authorities to find ways to enforce these things, not us.