Turns out people have looked at this:
Although smoking cessation is desirable from a public health perspective, its consequences with respect to health care costs are still debated. Smokers have more disease than nonsmokers, but nonsmokers live longer and can incur more health costs at advanced ages. We analyzed health care costs for smokers and nonsmokers and estimated the economic consequences of smoking cessation.
CONCLUSIONS
If people stopped smoking, there would be a savings in health care costs, but only in the short term. Eventually, smoking cessation would lead to increased health care costs.
from:
The Health Care Costs of Smoking https://www.nejm.org/doi/full/10.1056/nejm199710093371506
So from a strictly cost point of view the government should have no interest in stopping people from smoking, I'd guess the same is true of vaping. And if the lost tax revenue on cigarettes and vape were taken into account abstaining likely costs us even more. Not saying this should make a person smoke, but rather just saying, for the government, the money is not a good reason to get people to stop.