At this point, I don't use a lot of my trading capital, yet am holding it in the account 'just in case.'
I see plenty of people saying that they routinely remove it from the account "just in case", so your perspective is refreshingly different.
I don't think you can ever have "excess cash", myself, to be honest ... but I suppose I know what you mean.
I've been known to buy old musical instruments (not terribly expensive ones) and vintage wines. Decent string instruments seem fairly reliably to appreciate in value three-fold every 7-8 years, but you definitely need good advice about what to buy.