Its use will increase more and more as time passes and I believe with payment methods that support crypto along fiats things will get better and maybe fiat users will become curious.
There is coinpayments too which works great and allows multiple currencies. The easier it becomes to spend crypto the better.
I also think it don't need to be legalized.
If the government did not legalized these cryptocurrencies, that means they do not care about it and the people in their country using it. Government has nothing to do with the scams that will happen with them, they are not protected by the government. I think before cryptocurrencies, mobile payments will be the first one to popularize.