Some of the shops accepting BTC in some countries do it just for clout-chasing, just to attract young customers like you to their shop.
I actually doubt that.
Bitcoin is a risky investment much more a risky payment method. These businesses need to have a profound understanding of bitcoin and how it works and how it could benefit or cause harm to their business.
Its not a simple marketing strategy because they are quite literally putting everything on the line. I think if a shop decided to put bitcoin as one of their accepted payment methods they genuinely believe in btc and would want to be part of it.
For a country like Lugano, El Salvador, Brazil, England that have accepted to regulate the activity of cryptocurrency users in their countries respectively, I don't think shops or businesses there would find it hard to accept BTC or even any altcoins for their transactions, because it is a currency for exchange and payments that may include purchase or taxes.
Where I think accepting BTC or cryptocurrency in shops or businesses isn't viable, is when such businesses exit in a region where crypto currency is banned or not accepted and regulated by the government. Unless it is from well known customers and trusted P2P traders or investors, shopping with BTC or cryptocurrency is a kind of option that is specifically requested or available to real crypto currency believers.