i think its pretty hard to define between a pro and amateur in trading but you know it when you see it. i think it is a bit of cop out someone just making £100/week. if it works, go with it. the money question matters more as some ways of trading aren't open to people with no money...in fact almost all kinds of trading aren't open to people with no money. saying your a pro if its your primary source of income really complicates it.
another way to define pro would be by consistent success in outperforming a benchmark like an HF index or SP 500 or futures index...benchmarking is total bull but if you have a 5 year record of monthly returns then it wud be clear if you knew what you were doing or not. but $ returns are also useful though cos a good trader shud know when to take risk. like if your making 5% a month with little volatility, you shud try and get some leverage, if someone didn't they probablly don't believe they can trade.
another way to define pro would be by consistent success in outperforming a benchmark like an HF index or SP 500 or futures index...benchmarking is total bull but if you have a 5 year record of monthly returns then it wud be clear if you knew what you were doing or not. but $ returns are also useful though cos a good trader shud know when to take risk. like if your making 5% a month with little volatility, you shud try and get some leverage, if someone didn't they probablly don't believe they can trade.