I actually think Gravik was a solid villain, much more well-rounded than the usual Marvel fare.
And like Killmonger.....he was kind of right. I mean let's be honest Fury absolutely used and dumped his people. And realistically his views on humans was probably correct...as soon as humans found out that Skrulls lived among us....the shootings began. Now of course you can counter and say "well if the skrulls hadn't done terrible things this wouldn't have happened".
But...lets dig deep and really think about our species for a moment, is that really true? Do you think humans would really accept an alien race living next door that could literally change into any person at will, pretend to be your friend, your family, your lover?. I don't, I think that kind of violence was ultimately inevitable. So Gravik's has a solid point.
Then combined that with the absolute rage he feels at Fury. This was effectively a father figure that literally made Gravik kill for him, abandoned him, and broke every promise he made to his people. Yeah that's going to warp you.
But like so many charismatic leaders before him, Gravik just started to believe his own hype a bit too much. Started pushing his people a bit too far, dismissing any criticism, killing anyone who stepped just a bit out of line. We see that with the internal coup that failed, and its an all-too-common tale that is very understandable.
Frankly my only issue with the character was that he died too much like a chump. Literally one of the strongest creatures we have seen on screen killed in mere minutes.... a real waste.