Well, okay. Let's keep it simple then... How much does someone need to know to call himself (or herself) a computer expert? How do you judge if someone is an expert or not?
It's not up to the individual to decide whether they consider themselves an expert or not but it all comes down to what your peers think ...

Expert
The term is widely used informally, with people being described as 'experts' in order to bolster the relative value of their opinion, when no objective criteria for their expertise is available. The term crank is likewise used to disparage opinions. Academic elitism arises when 'experts' become convinced that only they understand their field of study (or anything at all).
That might explain why some people steer from using that word ...

It would have stayed on topic if you had not used the word "expert" ...

Just out of curiosity did you intentionally use that word so that it would cause some discussion amongst the members ???