Bitcoin can be used for anything including gambling and bets. Bitcoin blockchain allows all people and companies to use it for transactions and on Bitcoin blockchain, people can do many things that are their individual interests or their companies' interests.

If Bitcoin blockchain restricts any person, any company or prohibit any trade relates to anything like gambling, trading, or activities that consider as illegal, it will become a censored blockchain while it was not designed for this purpose and it has never been like this in its blockchain operation since 2009.

The appearances of gambling companies here in this forum in signature campaigns are likely because gambling companies easily get profit and they don't see anything harmful for their company budget by advertise their brands in signature campaigns. Such advertisements can bring traffic, inflow of money from users an and maybe help online gambling companies get more profit.