Few of us can afford not to have insurance, hence the consistency in the content of the replies in this thread.
Yes, lots of us book Disney far out. I booked this year's trip, I think in April last year so more than a year out. BUT all I would lose for booking Disney so far out is my £100. I can get right up to 8 weeks prior to travel before I start to lose more as I get closer to the trip, by which time my insurance has well and truly kicked in. Insuring Disney is not an issue. It won't bankrupt me to lose £100 (my £50 per person deposit).
However I booked my flights 10 months out so I could, and did, get an excellent insurance policy immediately the day I booked them.
I can see you are bent on booking your flights really early, but I think you really need to ask yourself if it is only you who you are trying to convince that you need to do so. If you were my closest friend and asking for an opinion, I'd tell you I think you stand to lose more financially by booking these flights so darn early. If something goes wrong, you risk losing everything; and to stop that, you are going to pay more to keep yourself covered. Very few people on here have had to cancel a trip due to not being able to find flights at prices within their budget. Nobody is criticizing you, but many on here do this year upon year, some more than once a year, and so far nobody has supported the idea of booking these flights so far out that you can't protect them adequately. I can't get more upfront than that. Hope it doesn't read as snippy, as it's not intended to be.