Bezos’s superyacht, which likely will cost upwards of $500 million to build and have its own support yacht with a helipad, is the latest accessory — along with the Washington Post, the movies, the tabloid scandal — heralding the Amazon mogul’s transformation from geeky technologist to globe-trotting megabillionaire. It’s an indication of the enormity of a fortune that’s accrued even faster as the world has been upended by a devastating pandemic.