At least you realise it's a gambling addiction so that's a huge first step already done. Apart from going to a therapist, have you tried finding another occupation that could replace it ? Like collecting something, instead of buying random stuff hoping to get something you like/want you could only look for specific things to complete a set. Like for Pokémon for example, you would buy the complete set of your favourite Pokémon (every card of it). Instead of buying packs you only buy these specific cards from eBay, garage sales, etc. It's still random (you don't know when/if you will find what you want) but you only spend money when you find what you're looking for