They would make more profit, if u could use spotify with it.
You don’t understand how Apple makes money, so you?
The whole point of a vertically integrated ecosystem is that you will never have a large user base. You are offering a highly differentiated product, which means that by definition, you can’t reach everybody. But it also means that you have a group of loyal users who are willing to pay handsomely for your products because it represents a perfect fit for them.
The HomePod, like the Apple Watch and Apple TV, is an iPhone accessory. Its purpose is primarily to add value to the Apple ecosystem, thereby making it more attractive to stay within the Apple ecosystem (and consequently more unpalatable to step outside of it).
Apple is betting that this product will incentivise enough users to stick with iPhones and (to an extent) Apple Music. So they lose some sales from users on Spotify or those using android phones. No big deal. You win some, you lose some, and the trick here is making sure you win more than you lose.