First of all, no one is a lost cause. Having everything you would want in an materialistic sense, doesn't make you happy. Happiness is something you receive by practicing compassion towards others, and by looking inward and to start asking yourself the big questions; Who are you and what do YOU want. Try to find out what causes this mental suffering, and always remember that life is not perfect and it never will be. Don't focus on the past, and don't make yourself go crazy of what might be ahead of you in the distant future. When you feel like it gets too much go outside if you can and just take a walk in nature, with no technology with you such as a phone. Don't rush, but take your time to calmly look at nature how it is without thinking about the past or future. Just look at that what you see in the now.
If you need advice on anything or someone to talk to, you can always send me a message. I wish you a wonderful day.