Not always so.
I was involved with the C Of C 's unsuccessful fight against anti-smoking ordinances and found that after it passed it actually had a positive effect on most business. I knew the owner of a restaurant that converted her business to non-smoking voluntarily before the smoking ban and doubled the revenue after a few years.
Another restaurant that vigorously fought a pending city ban in restaurants also experienced an increase in revenue. That establishment at first went to the expense of establishing a closed off smoking room allowed under the ordinance but converted that room to non-smoking because it did not generate the business expected. They do still have a few tables outside for smokers that are not used much.
One of the local bowling alleys set up a smoking room and the owner told me league revenues increased after the ban went into effect. He said some bowlers that had went to the non-smoking bowling alley across town came back when he made the change. He was also against the ban prior to it's passing.
Even the president of the are restaurant association that was very vocal against the ban told me a few years after it passed that he now thinks it was positive for the business that changed.
Well, you don't state what state or town you live in, so I can't make any comments on why this is.
We do know that all across the United States, a lot of private restaurants, bars, bowling alleys and bingo halls have closed because of the forced smoking ban.
If you can give me a hint about where you live, I will look into it and see what I have on that area. Right now, I have you living in Utopia, and it's not on my map. :)