gambling is often seen as a harmful habit.
The correct statement here is that gambling is what is harmful and not the activity in itself. Gambling is neutral. It depends on how you choose to look at it based on your experiences or what you have been told. Gambling is just like eating. If you eat moderately, it will nourish your body and serve you well. If you binge on your food without control, you will become obese and suffer numerous health challenges.
in a completely free society, should someone be prevented from providing gambling services for the good of society?
No. As long as it is not illegal and withing the law, no one should be prevented from providing gambling services. Gambling operators are also employers of labour. They also bring in revenue for the government. It is a good business.