Of course every product will top out. At that point profits don’t increase, but why should they?
There is no law that says that your profits have to get higher every year. If a hundred million in profits was good last year, it’s still good this year. In fact, maybe the market, taste, technology will reduce your sales or even drive you out the market altogether. Lots of companies go out of business when better products and other sellers appear.
That’s a good thing about capitalism. New/better replaces old/worse.