I started as Senior developer and was no.2 in the company under the manager, but the company was owned and invested in by someone else. After a few years I became the manager and that's when we really ramped up the turnover. Income from support contracts was about £100K per year. System prices ranged from £3K to 30K (it got installed in the House of Lords and the House of Commons for example). We only had 4 staff members on average and made a great net profit after salaries each year (surprisingly your 30% is a pretty good estimate). I had a good wage and profit share but the profit was not mine, it was the owner's. However, I had built that company and the software over the years and knew I could do it again but on my own, so I started making games. 3 years later it's going well, but I've not turned over £2,000,000 yet ;-) However, it's early days.