Of course bitcoin is used for illegal activities, but so is the US dollar.  All forms of currency can be used for things that are illegal.  I think we need to also look at all of the good things that bitcoin can be used for such as sending money cheaply to other parts of the world.  We also have almost full control over our bitcoin but fiat is controlled by governments and banks.

Bitcoin will be used for good as well bad things the same way it happens for several years with fiat, soo nothing new here, besides its harder to trace the people who are under the dark marketplaces.

of course it is a natural thing and very logical if one uses currency bitcoin for something they need, whether it's illegal or legal is up to them, the difference with another currency bitcoin is more secure and hidden, that's why I see a lot of issues who came on this matter, I think it is not a problem right ?

Yes it is used for some criminal activities but we should not care about it at all because this is life, the fact is that every currency has this down and dark side.
I do not care and I think its also logical and not so bad too.

Yes, like every currency, Bitcoin is being used for illegal activities. However, I'd say the ration between "clean" money and "dark" money will be higher tha with fiat, where at leat 1/10 of the total cash was ever used for illegal activities.