I would not equate the H1B to slavery, but saying H1B holders are free to quit and work elsewhere whenever they like is akin to saying anyone is free to make a million dollars any time they want..Its true in theory, but not so straight forward in reality. For starters many employers will NOT hire an H1B holder, so that narrows your options right off the bat. The companies that do hire H1Bs will often only do that for certain positions, so your career plans had better be exactly in line with those positions..