"It exists" is correct

"It doesn't exists" is incorrect, exists becomes exist, "it doesn't exist"

Edit: apparently the "does" in "doesn't" absorbs the conjugation, returning the verb to its infinitive form

More:

"They arguments doesn’t hold" typo they ought to be the, those or their, not sure what you meant. Since arguments is plural you want don't, not doesn't, alternately "the argument [singular] doesn't hold"

'national ones creates money' subject verb agreement again, either one creates or ones create

"bitcoin pools mentioned ahead" ahead doesn't quite apply to comment threads, like on a road you have cars in front (ahead) and in back (behind), but with comments it's above and below, cause you scroll up and down, not forward and backward