Thumbtack.com Provided me with a "pro" who is a criminal San Francisco California

I hired a custom cabinet maker through Thumbtack.com and according to Thumbtack.com, they had verified a background check.  After, 3 months of waiting for my cabinets to be built and installed, the cabinet maker never shows up for installing the cabinets.  He had given me design specs and even created a sample of the cabinet and door style I had chosen.  Everything seemed legit and thinking that this person was recommended thru Thumbtack and that on Thumbtack's website, it said his background had been verified.  I Googled George Meszaros, Clearlake CA and found he has an extensive criminal record.  Now, Thumbtack is telling me they are not responsible.  I have paid the cabinetmaker $17,500 for custom cabinets in my kitchen, pantry, laundry, and rental unit downstairs.  I have no kitchen and all my plans for having my old parents to come stay with me from Florida for the Thanksgiving and Christmas holidays are shattered.  Also, I was expecting to rent out the unit downstairs for in order to help me pay for my mortgage and now that has also been shattered.  This has affected me emotionally and financially in a very big way and Thumbtack thinks it has no responsibility in this.