I have always been interested in how difficult it was to mine BTC in 2009, but there seems to be no clear answer.
In 2009, the difficulty was 1. The number of blocks a computer could mine at the time varied depending on many factors, but a CPU miner had a hash rate of up to around 3 MH/s. With a difficulty of 1, that corresponded to a maximum of about 60 blocks per day, or 3000 BTC/day.
In 2010, the difficulty rose quickly as more people began mining, and so the number dropped. By the end of 2010, the difficulty was around 15000, so that same 3 MH/s CPU miner only mined 0.2 BTC/day.
BTW, the average time between blocks can be estimated with this:
time in seconds = difficulty * 232 / hash rateSo, the average time to find a block for a 3 MH/s CPU at a difficulty of 1 is
1 * 232 / 3000000 = 1432 secondsIncredible insight, if only I was lucky enough to be aware of Bitcoin back then. By the time I finally got in, in 2015, the days of solo CPU Mining were a thing of the past. Congratulations to were involved that early, must feel good.