I have never purchased travel insurance and I have had an unexpected health emergency that was not a pre-existing condition. That trip was mostly charged on my Amex plat and I didn't remember that coverage so approached all the suppliers directly. Most made an exception although some required a doctor's letter and the non-refundable portions totaled about $600 or so, mainly because one lodging supplier refused any refund (Landmark Trust, a British charity).
That was way cheaper than had I been buying travel insurance all along. I hear that the commission on many of those policies can routinely go as high as 35%, which tells me all I need to know.
I have however noticed that luxury and high-end city hotels have been hiking up their cancellation times to as much as 72 hours in the last year, which is frustrating.
So I'm a strong NO on this insurance, but then I am willing to make the effort required to ask these companies to waive their restrictions if something bad happens and have so far mostly succeeded with that.