Younggun
Sounds like fall instructional league, I don't know about pitchers but son as a position player was invited several years and he always went, not everyone is "invited" to instructs. The club is giving you the opportunity to improve and unless you have a good reason not to I think its in your best interest to attend.
How would you view it if you were an employer and offered an employee add'l training/education and the employee turned it down ?
Floridafan
If the player is taking home $200 wk he is doing better than most
Son's 1st full season he grossed $850 mo, after taxes the team took $400 mo for rent of the motel room (which he shared with another player)then he payed club house dues. He had less than $100 wk to feed him self and since he was staying in a motel he had to eat his meals out. He had to buy a bike so he could get to a place to eat!