White tigers are falsely marketed as a highly endangered species. They are bred for cash not conservation. A single male white tiger was imported into the US decades ago and all of the white tigers there have been inbred from this individual. Inbreeding is quite common in captive tigers but can cause significant health problems.
White tigers are not a separate subspecies of tiger. There is only one tiger species and two recognised subspecies, the Continental and the Sunda.
A genetic mutation called leucism causes a tiger to have white fur. In the wild this can be a hinderance as it destroys a tiger’s natural camouflage, reducing their chances of survival.