A custom built frame perhaps of titanium. Add some bling and accessories. Have your name painted on the bike, get carbon wheels, high power generator light. Enjoy the process.
A carbon mountain bike with custom wheels and XX or XTR can make it to $10,000. You will have one of the lightest fastest bikes available. BMC, Niner, Pivot, and Tantrum are options.
A bike with a Rohloff hub, custom wheels and a few speciality parts can hit $10,000 easily. We have built a few and they are used for travel, mountain bike excursions and just to have fun.