I have 15k in unpaid invoices. 5k of which is over a year old. Everyone has contracts. Considering getting a job and just giving up the biz.

Take legal action?

Take legac action, and I hope the best for you

@rutee07 now this is an idea!

There is a service like factoring or similar name where you sell the invoice (right to be paid) for part of its sum and the factoring company will take the legal action, not you.
You can sell the debt to debt collecting companies, like banks do.
You can report your business partners to company holding a credit blacklist, so in future they will have huge problems with getting a loan.
Of course you can sue them. I think you can also publish the information in the internet. Publishing information that company X having CEO named Y is doing thievery and not paying their business partners.

@mt3o Non recourse factoring. I'm in the trucking industry. That's something I should look into for web development.

Why don't we, as industry, kill projects that are not paid? We should put them down on the client's server and perhaps release the work as opensource.
We should include kill-switch in the agreement. Sell our services "as a service" like Amazon does. And give "discount for payment before the due date" like mobile operators do.

You know, clients are the main reason I don't freelance. As employee I get paid every month, have paid sick leave, social security, holidays and other stuff. Less freedom, more safety.