I wasn't able to find something outlining just the sales of the 4000 series cards, but the first graphic of this link at least has their total desktop GPU sales, which comes out to 30.34 million in 2022. Let's put a fraction of hundreds of millions at 5% of 200 million to be generous to your argument. That's 10 million. Then let's say these people upgrade their GPUs once every 3 years, which is shorter than the average person, but the average person also isn't buying top-of-the-line GPUs. So 3.33 million. 3.33/30.34 is 10.9% of sales.

So even when we're looking at their total sales and not specifically just the current gen, assume 200 million reddit users a month when it's closer to 300, and assume the people willing to shell out thousands of dollars for the best GPU aren't doing so every single time a new generation comes out, we're still at 11% of their sales.