A tentative summary, please add anything I may have forgotten
- Free account: one account
- Paid account: unlimited account
- What is forbidden: self-referral, bots, paying people to use your referral link
- My spreadsheet answers a lot of question about (increasing) profitability, number of clicks...
- Tip: if the BTC difference between two levels are too high for your taste, you can by several account of lower level instead. Example; you have a 1 BTC account, you want to upgrade, but 5 BTC is too much - but 2 BTC would be fine. You can buy a second 1 BTC account, and you know have 2 BTC. If you want to move from 1 BTC to 1.25 BTC, it works the same - the granularity is 0.05 BTC, the lowest paid level (actually less, since there are discounts, too)
Maybe you can add in "What is forbidden:" pay people to use your referral link!
I thought of it and forgot it. Thanks for reminding me, I have updated