Having been in the trade for 45+ years now, I can confidently tell you that most players use only a fraction of what their instruments can do. It's always been that way. That's starting with electronic organs in the late 1960s, over 10 years or so before we saw the first Yamaha keyboard. As instruments got better, bigger and inevitably more complex, that 'fraction' became more like a 'tiny fraction'. But that's not really a problem as each player will use a different fraction.
Even the 'power users' don't use everything. We might use just about everything that we're interested in, or that we like, but definitely not everything!
The advice given to customers when I started all those years ago still holds true today. Buy an instrument that you will grow into, not one that you will grow out of. So, even if you think your Genos, S975, CVP Clavinova or whatever is 'overkill', my advice will always be to stick with it. If you sell it and trade downwards, at some point there's a good chance that you'll kick yourself when you do want that sound or feature that you once had but now don't.