This company holds a valuable monopoly that's easy to understand.Warren Buffett is well known for eschewing advanced technology stocks. That's often led him and Berkshire Hathaway (BRK.A -0.13%) (BRK.B 0.14%) investors to miss out on some of the most lucrative investment opportunities in the market.One of the biggest winners of the last few years has been Nvidia (NVDA -2.79%). Its GPUs are essential infrastructure for artificial intelligence (AI) training and inference. As a result, it's seen demand soar ov ...