Yeah, I need to make a simple spreadsheet and try and figure it out. The problem is that the risks are high: the usual figures are less than 1 in 10 businesses

Yeah, I need to make a simple spreadsheet and try and figure it out. The problem is that the risks are high: the usual figures are less than 1 in 10 businesses succeed or that a 30:1 payout is the minimum sensible financial payout (VC figure). Winning is hard even though we don't have a CGT. Marginal tax at 39% doesn't encourage marginal business building. And once you have the house and the bach, the marginal utility of money drops for an individual: the marginal happyness from the next million is a lot lower than the first million (also see "income satiation"). The discount rate, and the personal cost are other huge factors, and the average person doesn't like a financial winner. Investing money and time in a high risk activity like starting a business is not fiancially sensible from what I have seen. We do it to chase status, not because it makes sense on a spreadsheet.