In particular for larger amounts of money. Many countries have deposit guarantees for smaller amounts, so for most individuals it wouldn't make any sense to buy negative-interest bonds. For example, someone in the U.S. who wants to store $250k with a government guarantee can simply put it in an FDIC-insured bank account. I believe Germany is similar, though with a lower €100k guarantee per account. You can go a little higher by having multiple accounts at different banks (at least for FDIC insurance, the first $250k at each separate bank is covered). But if you have $10m or $100m to store, government bonds become the only practical way to get a similar level of insurance.