Let's be honest, lots of people partake in things one might refer to as vices e.g. gambling, drinking, smoking. Putting the advertising aspect aside, if any of these were banned outright all that would happen is driving the activity underground, in the case of gambling even more so than parts of it already are.
Looking at the family backstory, she further expanded the business her dad had started and to an extent took her own gamble by mortgaging betting shops he owned to build the Bet365 brand. It paid off, in a big way, however could equally have failed. I think she's also known to pay all or indeed much of the tax she's liable for. So you can imagine how much that'll be.
I say good luck to her, actually I say good luck to anyone that succeeds in building a business, as long as the activity isn't illegal.
Do some people have problems / an addiction to gambling? Yes. As do people with drinking alcohol and smoking. Should that correlate to an outright ban? Not in my opinion. Many people manage their gambling activities perfectly well, setting limits and/or just having the occasional flutter.
If I started a business today that grew exponentially and x years from now I was taking a £500 million annual salary from it, as long as the business activity was legal, I wouldn't feel guilty in the least and would sleep like the proverbial baby.