1st: You don't have to have 75mbs internet - you like to have it
just like I like to have 100mbps internet
As for promo pricing, you don't have to switch ISPs every year - merely threaten to do so is sufficient.
Lets say I have a "triple play" combo from my cable company: basic broadcast TV (no cablebox), 100mbs internet and phone service. Everything I pick up the phone to call cable company. I ask for Disconnects Department (don't bother with regular Customer service). Last time (this august) I even went straight to point - extend the promo for one more year or I will have to disconnect services.
If drop internet to 50/60 mbps down and cancel other services (surprisingly I still do use on rare occasion both) I could save $10-15 month, but it's not worth it for me at price of internet speed drop.
BUT, technically for Netflix 4k streaming you only should need 25mbps down...
p.s: With my 3play promo I pay about $99/month - I think it's ok deal for 100mbs internet, basic tv and phone (which I use for faxing on rare occasion)