Like you say, he was first, and now he's sort of a legend, and that you cant take away from him.
But he has one more huge advantage:
He is the perfect diva!
He can play, and he knows it.
If you go around claiming you're the fastest, the ebst, the most good looking, the hottest, nicest, wildest, richest guitarist in the universe, and Yngwie has done this for over 20 years, then people notice him.
Because after all, Malmsteen is one of the worlds most famous guitarists, but I dont think everyone actually LIKES him.
I bet a large percentage of his "fans" really REALLY hates him.
He is a show artist with a HUGE ego, and that has made him one of the most famous (if not the most famous) guitarist ever.
Example:
Yngwie malmsteen is strutting around on stage as usual, and while playing he flips his guitar and show the crowd the ferrari logo he has on the back of guitar.
Then he screams in to the mic: "I've got 2 of them!"
Hehehe, you gotta love him.