site work is just a job now, you might be classed as self employed but you'll only earn what cards in lads earn once you take into account your added expenses as a self employed subbie, insurances, van costs etc.
Someone once said to me that it was a conspiracy by QS's and contracts managers to drive down our wages because we were earning more than them, i thought he was talking crap at first but the more i think about it it makes sense, they are supposed to be higher up the chain than us so it must have pissed them off to see young lads earning more than them on site.