Even if they did, it would be normal because they are business, not a charity. Like you, are you willing to invest tons of money and intelligence to create a product and let everyone use it for free without caring about profit? Also, even if they stop offering the free version and start charging, I bet it will still be significantly cheaper than chatGPT and the quality will not be any less. This will benefit consumers, why should we be upset with them?
The market competitors policies will tell whether these AI bots will remain free or there will be a fee to use them. If there is a free version of ChatGPT available then I don't think DeepSeek will do the bold move of charging users. Right now there are three versions of ChatGPT available free, Pro (20$ per month) and Pro (200$ per month) and to me DeepSeek will also follow this pattern once there product is matured.
To be honest, they just started it, China didn't had any proper AI before this, and they are already quite far behind as well. That doesn't mean that they are going to end up being worse, they will get better and improve eventually, but when you have something worse, and the other one keeps innovating and improving, it would be hard to be equals.
This comes to fee as well, right now it's free, because it's worse, and if it stays worse than it will continue to be free, after all why pay for something worse when you can pay for something better? The idea should always be "this is worse but free, the other one is better but expensive" and in that case we could always end up with chatgpt having a competition. The moment deepseek starts to charge a fee, they will lose all consumers outside of china.
My personal experience with DeepSeek is fine and I will give 7/10 to DeepSeek. I haven't used ChatGPT in it's initial days of launch so can't make a one-to-one comparison between two. The AI model generally learn and improves over the period of time as they answer more queries. If the development team of DeepSeek keep working then there AI model will improve more and they must be well aware of how much improvement is required at the moment.