"Might your travel insurance cover a booking lost because of a strike? "
If a booking is "lost" BECAUSE OF A STRIKE (i.e. if the departure in question is cancelled), SNCF will refund or exchange even normally non-refundable tickets, provided that the request is made prior to the date of travel (https://be.oui.sncf/en/train/strike).
If, on the other hand, the booking is for a NON-STRIKE day (or non-cancelled train on a strike day), which is what I understand to be the situation, then the train operator will not refund non-flexible fares, but neither will an insurance company cover a cancellation made when the train was running but the policy-holder was afraid it might be over-crowded/otherwise affected by the disruption of OTHER services/ on other days.. Therefore it doesn't matter that the OP has no trip insurance, as it wouldn't have paid out when the train was running (or, if the train operator would have refunded this anyway, even if it wasn't)!
Edited: 5 years ago