I came here for the things you can't easily put a price on - like the weather, local arts, music, and culture. Also driving into the mountains, or down the coast of California. Chicago is no slouch for fun but cold days like this make me glad I'm not waiting for the 'L' outside anymore. SF weather is generally magical.
Being in a top US city still gets me direct, reasonably priced, and frequently scheduled nonstop flights to family/friends in places like Chicago, Cincinnati, Los Angeles, Seattle - not always attainable in some of these smaller tech hubs (like Portland, or Austin.)
When people move here, there is a constant worry about how much money they will make or what company they work for - I didn't sweat it.
Within a month after arriving, I landed a great career. I spent the last two years exploring other hobbies and interests, and nurturing healthy new friendships.
Biggest tip I can give - It's nice to get to know people who've been around here for a while, they've seen it all before. Show an interest in your local community. Volunteer your time but branch out of tech. Get to know people here in all walks of life; show compassion You just may be liked enough by some old school San Franciscans that refer you to one of their friends; who rent you their old place (with parking and views on Twin Peaks) for $1200. It worked for me.
San Francisco is not an expensive city because of tech alone, it's always been a bit on the expensive side; as there's no place in America like it.
Of course this is my experience. I merely bring it up just as a reminder that there's so many things to focus on when decide whether or not moving here is worth it. The questions that guided me in my decision to move here were:
What are my goals long-term? What made me decide to move here? What is my contribution to the local community and society - outside of working in tech? Will I ultimately grow as a person; both personally and professionally? Is there enough other activities around that will keep me from being bored that I'll enjoy?
My $.02.