In many areas of the United States, there is only one ISP available. Part of this is due to the high cost of entry, but the ISPs also have a past filled with rather shady activity. Verizon was given federal money to expand their network, did a fraction of the work, and then used their influence to pocket the rest. Comcast will throw lawsuits at new ISPs in order to bankrupt them.
Because of this the ISPs already use their monopoly position to take as much money as possible via data caps and bandwidth. I believe Comcast is on record as saying data caps aren't needed, but no one can stop them. The reality is ISPs are some of the most greedy, unethical companies around that exploit their monopoly position for their bottom line. Either regulation needs to be in place or the government needs to incentivize and protect new ISPs.