The problem is that the ISP resources are shared resources. Some day we might all have 1Gbps+ fiber to our houses but today this doesn't exist. Many parts of the network you use to access the internet are common to some other set of people. So if you were to saturate your internet line, your neighbors (or possible more people) would have seriously deteriorated access. There is no way around this problem without upgrading the last mile connections everywhere, which is expensive. You're essentially paying for the most profitable and acceptable internet the ISP is willing to provide.

Maximum throughput and quality of service are not their goals. They want as many people as possible paying for service on a line they paid $X to install. And they get this by being able to throttle their user's traffic in order to allow as many people to use the same line as possible.

What you're saying is basically the same as the "unlimited" argument in terms of internet access or even cell phone plans. You don't have a personal internet connection just for you that you can use in an unlimited way. The internet line run to your neighborhood is essentially zero sum. If you take a huge chunk of the bandwidth, then other paying customers get less. Charging you more doesn't help unless you fund entirely new network lines and installation. They want everyone to have an equal size of the pie. You can't have a dozen households sharing a connection to the internet and all be streaming netflix in 4k. There simply isn't the infrastructure to support that right now, in most places. No matter how much you're willing to pay.