Recently, Eric Peterson from Valve gave a presentation. He talked about the events (sales) and shared statistics.
According to the available data, Steam has an average of 75 new buyers per minute:
"From August 1, 2024, to August 1, 2025, an average of 109,000 new buyers made their first purchase on Steam per day. That's more than 75 new buyers per minute. Peterson compares this to the Munich Olympic Stadium (capacity: 75,000), explaining that even if the stadium were filled every day, it would still need 34,000 more people."