Working in a theme park is not a typical kind of job. This is especially true if your park includes animals, they require care 24/7, open or closed, good weather or bad. The folks that stay around are very dedicated and have decided that traditional summer holidays can be celebrated other days of the week and that not having weekends off can be a good thing for errand running - less crowds on weekdays.
At SeaWorld I am surrounded by just such a dedicated group of people, many that have been with the park 10, 15, 20 or even 30 plus years.

