Four years without leave sounds really overboard. In Europe the law mandates every worker to have a one-month leave each year. Not granting the leave is illegal

Four years without leave sounds really overboard. In Europe the law mandates every worker to have a one-month leave each year. Not granting the leave is illegal by the employer. Just keep in mind that in a capitalist society the work is never your everything as an employee. You're exploited one way or another and should detach yourself from the company in some way. There might be different circumstances where the employees' interests align better with the employers', but in general this fact always holds.