I am not really scared from any cryptocurrencies because I think that some politicians will bring a law which will not give access to bitcoin
Technically, you will keep on accessing and using bitcoins even your government will impose any restrictions. Person to person dealing of bitcoin is beyond the reach of government law. So, please come out of your fears.
some countries can also bann bitcoin if they see that bitcoin can deystroy fiat tottaly.
Some governments are emphasizing the importance of adopting digital economy. India is one good recent example. So, some government itself already has started destroying fiats. 90% of fiat usage will get replaced for sure.
bitcoin price growing speed is decreased really much
It is highly dependent on adoption rate. If you spread bitcoin, it will have price appreciations quicker. So, it can not be a danger. Always slow and steady is preferred than rapid growth.