because
1) everything you need to know is either freely available on these and other forums. If you check out the FAQs, then read the books that are recommended in the Book section and elsewhere, you will have more knowledge than a seminar will ever give you.
2) there are professional traders wiling to share their methods, even their live trades, with you on these boards. That is priceless information and experience ! Check out RhodyTrader, trader_dante, Captain Currency , to name just a handful
3) if the prik who is running the seminar/training could actually TRADE, that's what he'd be DOING for a living, not ripping off naive, innocent newbies who believe he will provide them with the Holy Grail, a quick, sure-fire way to easy money.