13 Years ago a regular PC could mine over 50 BTC in a day!

Satoshi talked about the very first automatic difficulty adjustment of the proof-of-work network that took place on December 30th, 2009.

"We had our first automatic adjustment of the proof-of-work difficulty on 30 Dec 2009.

The minimum difficulty is 32 zero bits, so even if only one person was running a node, the difficulty doesn’t get any easier than that. For most of the last year, we were hovering below the minimum. On 30 Dec we broke above it and the algorithm adjusted to more difficulty. It’s been getting more difficult at each adjustment since then."

One user remarked that he generated five Bitcoin blocks in one day using a Pentium processor in 2010.

For context – miners back then used to receive 50 BTC for successfully adding a block to the network because the latter hadn’t yet undergone the subsequent halving events.

Quick math shows us that the user received 250 BTC in one day, mining BTC on their Pentium processor and other received 50 for then "regular" processors.