Am i allowed to travel without travel insurance?

Travel insurance is optional, it is there to pay for any medical expenses, damages, theft etc in the country you are visiting, or whatever country you select.

The airlines encourage the purchase of travel insurance, not because they receive some sort of commission. But because it allows the insurance company to cover any medical expenses, special transport requirements, etc. And in the event of an illness onboard, it is wise for the airline to offer some sort of optional protection to passengers in the form of insurance should medical requirements on the ground be required.

For a skiing holiday it is wise to take travel insurance, but it is optional and the cost of purchasing insurance is small compared to what you would have to pay due to medical reasons, theft, etc.
If you intend on taking any high risk activities abroad, it is wise to take out travel insurance.

Where there’s no travel insurance there’s always compensation if the liability is not on yourself.
ie flight delays, cancellations due to airline, volcanic ash, etc. Or any damages, injuries sustained on the passenger.
Plus travel insurance can be used to compensate someone else if you are the liable person inflicting costly damages on some else.

Travel insurance is there to compensate/protect the liable (person) based on the insurance paid and type of protection.