I have saved enough over the years to pay for one or two more European vacations.
Not exactly sure how much you expect to pay for travel insurance, but I have purchased it for every trip to Europe I have taken (a total of 15 not including those for work where my employer provides that coverage) and I have spent maybe enough to cover a few days in London which is no where near even one European vacation in total. I have not felt the need for extra insurance when traveling domestically.
The actual travel coverage is nice to have, but not so important compared to medical and evacuation coverage.
I have filed for travel interruption once when my flight back from Paris was delayed for 48 hours and I could not find another flight to get on. I followed the rules stated in the policy about contacting them as soon as possible and so on. They were able to find me a seat on a flight home in the same class of service as my original flight but a different airline for the next morning and found a convenient hotel at the airport. This cost me nothing extra. They also paid for meals and the taxi back and forth to the hotel. It was worth the couple hundred I had to pay for the policy. Of course, spending a couple more nights in Paris at my own expense would have been OK as well, work could have waited. ;-)
Now the important part. Medical. I don't plan on getting injured or sick while traveling. No one does. But it happens. You can slip and fall breaking any one of numerous bones. You can get food poisoning requiring a hospital stay. Anything that can happen to you at home can happen away. I have been lucky that in 50+ trips to Europe over the past 15 years, I only got sick enough to require medical care once, and that was handled by a pharmacist in Milan. The medical insurance covered the €10 charge for the medicines I needed. Evacuation coverage is even more important. Sure, there is nothing wrong with medical care in Europe and I would have no problem with being treated there in most areas. But if you do suffer a major medical issue it is nicer to be at a hospital near home to recover. There will be no language barrier. Your regular medical insurance covers everything it normally does. Friends and family can visit you when allowed. Being stuck in a foreign country until you fully recover from whatever medical issue you have is just no fun. And the cost of flying you back home can easily top $100,000 if your medical condition is serious enough. Also, most medical coverage you might have will not pay for the care you receive in the foreign country directly requiring you to pay immediately in cash or put it on a credit card and then file for reimbursement from the insurance later. European medical care is NOT free for non citizens.
EDIT: You posted the note about having medical coverage as I was writing this. I am leaving the medical coverage part for those who may not know.