It's like paying a $20 per month subscription for an all you can eat buffet (not quite accurate analogy, even the subscribed customers have usage limits!) have when you know you only want to eat the $2 salad once in a blue moon.
A subscription incentivises the company to lower cost per token and move customers to cheaper models to increase margins, even if it's at the detriment of output quality.
So...doing what every other tech company does? Or really, any company does?
"Overcharging" is true if you value your time doing all this at $0. If you don't know how to "plug an API into an app", which is a lot of people, then it's definitely worth it. If you know how to do this, how long did it take you to learn, and what is that time worth to you? Was there something else you'd rather spend that time doing? Is that time worth $20 a month to you?
For you, the answer sounds like it's no, you'd rather do it yourself.
* prepaid with your data
> A subscription incentivises the company to lower cost per token and move customers to cheaper models to increase margins, even if it's at the detriment of output quality.
Due to the high-stakes vibes of LLM development and the similarity between UI, customers can switch to another provider pretty quickly in case the quality drops significantly.