Ad sales are very lucrative.
Pretty much every TV is a "smart TV" now with built-in streaming apps. Why would anyone buy a Roku?
These additional devices only make sense if they are really cheap (and therefore subsidized by ads, just like the smart TVs are) or offer a premium experience (which would make them cost a lot up front.)
I have a Samsung Q-series TV now and tried using the smart TV apps for a while, but many were buggy and often had audio/video desync issues. I might blame part of that on the soundbar, but I gave up and got an Apple TV 4K and haven't had any issues at all.
I have a Roku, the “smart tv” I have is absolute trash and takes several minutes to start up the app based functionality. Once it starts, it’s glacially slow.
I’m sure newer tvs are faster, however I also have no desire to see my panel hit EOL due to a lack of software support when it works perfectly fine. TVs can last for years, and I see no reason why I should look to upgrade on a smartphone level lifecycle, when a reasonable dedicated streaming device is priced below $50.
Even leaving the cost of buying a new 60" TV aside, the effort of mounting a new one and disposing of the old one would make me hesitate to upgrade even though my existing one isn't 4K.
I'm pretty frugal and pay closer attention to free streaming services than the average person, and can say that in the last year or two, Roku has significantly improved its lineup of "originals." Although some are just hilariously bad (like Cypher from 2021), they're also getting some pretty good people like Samuel L. Jackson (The Fix) and Daniel Radcliffe (Weird: The Al Yankovic Story) making quality content.
When you own quality content, there's the potential to make money from it. Personally I think Roku may be attempting to build a streaming service eventually worth paying for. Maybe it'll be accessible from non-Roku devices, and maybe it'll remain free for Roku users to entice people in a similar way that Amazon Prime includes free Amazon Prime TV and Apple device purchases get some free Apple TV. (Yes, I know people don't buy an iPhone just to get TV... it's a perk).
Otoh, it works enough for now, so I'm deferring getting another Roku while I consider other options. I wasn't a fan of Tivo's android tv dodad, but a friend's android tv device for totally legitimate iptv from canada actually works nicely. (It helps that their custom launcher is minimal and fast)
Android based with gigabit ethernet is more likely to work well with my desire to run 4k blu-rays via the network (preferably with optional menus, definitely without transcoding which means dealing with peak video bitrate over 100mbps) and interfacing in a usable manner with mythtv for watching recordings.
I agree that Google of all big tech has the most to lose in the future regarding their internet search ad business, but Roku having ads and giving advertisers data makes a lot of sense for them.
This isn’t a dire times warning. It’s that the era of free money is over (and fucking hopefully for a long time), there will be some settling in to actually needing a business that makes money to stay around.