Help with FATE player that likes to make alternate characters

[Umbran]

First, the player will need to spend their high concept on the personality split and use those precious FATE chips to change personalities.

One chip for many more relevant Aspects may be a cheap price.

From my design point of view the ability to shift a personality to something more helpful, or from a compel to something less helpful, is actually the point of the exercise.

Yes, but I'm not sure it is *fair* to the other players. They don't get to shift to something more helpful, and they will generally help bear the cost of it being something less helpful. There's a definite risk of spotlight hogging to be watched for - even switching to something less relevant puts attention on this player, remember, as dealing with their irrelevance becomes the focus of play.

Second, more aspects has rarely a concern in play. In the games I have participated in rarely do characters even use all of their aspects.

Yes, now how often is that because they just don't have the right Aspects handy?

In Atomic Robo, a character may have 5 Aspects. In Spirit of the Century, a character may have as many as 10. Yes, in SotC, you are far more likely to have *something* relevant on hand, and the Fate Point economy rolls faster as a result. If you have a character with (effectively) 9 aspects among a bunch of 5s, you may notice a major difference in utility.

I play games for the social interaction and a bit of escapism, not to cause anyone harm or discomfort.

I don't say it out of fear that someone is going to intentionally cause harm or discomfort. I just find that the perpetuation of certain inaccurate stereotypes to be less-than-agreeable, and not something I want to support at my table very often. I don't support heftily racist or sexist portrayals at my table, either.