Most potential customers wouldn't ever think in terms as "justifying" a €20 purchase when the product is great.
ChatGPT (and competitors) is an incredibly high value tool, and €20 per month is nothing for somebody who wants or needs it. It's just a matter of if they use it enough to start hitting the daily limits.
This is why people are constantly moaning about paying too many subscriptions and why we have companies whose whole business is to remind you to not pay for stupid subscriptions.
As if paying constantly for a thing is normal and not dystopian
People are completely irrational when it comes to their personal finances, and hackers are the group who is most irrational of all.
For a few bucks per month you have access to artificial intelligence on a level which was completely unheard of just a few years ago. A revolution on the level of electricity or radio communication. And you are still complaining about price.
Consider if it's only habit that you have learnt from others. People talk all the time about the price of milk, eggs or gas, even though these things could double in price and still be incredible value. Then they turn around and waste enormous sums of money on completely meaningless stuff.
ChatGPT (and competitors) is an incredibly high value tool, and €20 per month is nothing for somebody who wants or needs it. It's just a matter of if they use it enough to start hitting the daily limits.