If you don't mind me asking, how much are you paying for cable TV ? What about your internet ? I'll presume your internet is from your cable provider too and if it is, the cost of internet-only
will go up. Many people pay $200/mo or more for cable TV and internet and if that's the case with you, you'll still save money if you're smart. We haven't had cable TV for 10 years but did have Dish Network with their lower-cost packages (Flex $35 + locals $10 + $30 in hardware costs). Switched to YouTube TV and it was $35/mo at the time but has quickly increased to $49 !

Still saving money over Dish though.
My internet cost was always separate so it's a non-factor in the above.
As far as Roku, it just so happens to be what we use. Many folks use Amazon Fire Stick or their smart TV's built-in apps. I have nothing against Fire Sticks, they simply didn't exist when I bought our first couple Rokus. As for smart TV apps, I'll never go that route (long-term). The TV manufacturers don't support their TVs for very long meaning the apps will become outdated or apps for new services will never exist on an older TV. If you replace your TV every 2-3 years, this might work for someone though. If someone replaces their TV that often, I question their interest in saving money though !