You need to answer two questions:
1. Are dive instructors professionals?
2. Do you tip other professionals?
You tip your dentist, doctor and lawyer?
How many years of education does it take to become a dentist, doctor or lawyer, vs how many to become an instructor??
How much does tuition cost to become a dentist, doctor or lawyer, vs how much to become an instructor??
How much is the starting wage of a dentist, doctor or lawyer, vs how much is the starting wage for an instructor.
Every full time resort bartender on Maui makes more money, before tips, than any full time instructor employee on Maui. Would you tip the bartender?
Yesterday I was offered a construction labor position that pays twice what I am making as a dive instructor. "Only" 40 hours per week, no annual membership, no gear expenses, no duty of care, no cleaning the head, no waking up at 4:30 AM.
Calling a dive instructor a professional is just using a word to justify your cheapness in most tropical locations!
If the operator charged enough to pay a living wage, none of the
cheap bastard divers would go out with that operator!