How to deal with taxes?

I mean one of main reasons that most people are buying bitcoin is to keep it as their money which is jot going to getvalue decrease like dollar etc...

But the problem is, if we are having it as a digital currency and it is a money rather a securities or commodities, so why we should pay taxes for it? And how do you deal with tax? Because it doesnt fair to me to pay tax for my own money, what did I do? I just changed my eurs to btc and keep hodl, and sometime buy stuff with, why should we pay tax for the money?

What is your suggestion? In general and in germany what is the legal solution

updated q:

1. What if I buy crypto and buy something with that crypto, lets say buying vpn with btc or trx etc... which in practice means I bought some crypto asset and sent them to some other wallet address, does it still considered to be my asset? How does gov tax that?or should I provide proof for what I did and tell gov that I bought something with crypto?

2. What if I send the crypto from exchange to another wallet address and then send it to a new wallet address? I just need to understand how does the tax work in these matter.

Does it just counts when I sell my crypto assets and they turn into eurs in my bank account?