Most dedicated bicycle policies are so expensive I reckon it would be best to put the money aside each month towards eventual replacement.
How much money are you putting aside? What happens if you have a loss in the first year? Or multiple losses in quick succession? Nothing wrong with deciding not to be insured, but you can't self insure unless your losses are reasonably predictable.
My one modest claim, for an accident rather than theft, paid out the equivalent of 19 years premiums, I'd have needed to have put away £560 pa to cover that, rather than paying the £88 premium.
My E-bike insurance cost nearly £600 for just over two years, with no claims, that could be considered wasted money, but it bought a lot of piece of mind. I don't think I'd have been as comfortable leaving locked up in the city centre if it hadn't been covered.