By Walt Hickey Vaporized Juul Labs — which sells highly addictive nicotine juice tied to a sleek vaporizer and, in the process, may have set back a generation of public health gains in youth tobacco usage — has seen their valuation seriously tank. Two years ago, when tobacco behemoth Altria took a 35 percent stake, the company was valued at $38 billion. Thursday, the company announced to employees that its valuation was now