The lactase itself may not be unhealthy but popping pills of it instead of letting your body try to do the work might be detrimental.
Like wearing high boots for hiking weakens your ankle over time and make you dépendance on the boots.
Discussion
That assumes the existence of a system which tries to keep a certain amount of lactase in your digestive system (which evolutionally would not make any sense, as having a higher amount has little if any downsides, and costs barely anything) and that such a system could become less effective if unused (unlikely, as this is basic synthesis)
So, no, most likely not
You sound lactose intolerant. But you may be right. Idk.