The comments were made in the wake of research showing that one in four travellers were not planning to take out the cover.
Travel insurance should essentially be compulsory for all people taking trips overseas, an insurer has said.
Endsleigh Insurance released strongly-worded new comments, saying that the cover was "vital" and that those travelling abroad without it were "crazy". However, the remarks are made at a time of severe economic slowdown - with the credit crunch and rising inflation putting the squeeze on people's budgets.
Indeed, American Express released stark research recently, showing that 24 percent of Britons are planning to go on holiday without taking out travel insurance first. Recent government figures also suggest that the cost of medical treatment for holiday injuries can be as much as £24,000.
Even a week's hospital stay in Greece can cost £5,000, the foreign office found.
John Boyles, account manager at Endsleigh Insurance, said: "If you travel abroad without insurance then in my opinion you must be crazy. It's vital. The costs can be enormous [if something goes wrong] and nobody is exempt or immune from something untoward happening to them."
He added: "Even if you are taking a shorter trip than you normally would, or you are staying in Europe rather than going worldwide, you absolutely should travel with travel insurance."
