[buboard]

This didn't come out of the blue. Thomas Cook is known to have problems for years and an impending collapse has been rumoured since months ago. Why did all these traveleres choose them is a better question

[bshimmin]

Because people often book holidays six months or more in advance, and Thomas Cook's financial woes weren't especially big news back then.

[differentView]

Because vast majority of people aren't aware of the financial health of the companies they purchase from.

[buboard]

it was in the news though, for more than a year