Please, note that you don't get insurance for your
data. If you have a house/flat/life insurance that includes insurance for your properties, as well, then you won't get any money for data loss, only for your computer's hardware, if it breaks. You
can get insurance for your data but, believe me, you
can't earn enough money to pay that insurance!
You're right, you're not obliged to back up your data every week. However, in that case, such very unfortunate data losses can - and, according to Murphy,
will - occur once. Actually, I'm not backing up my data every week either; I back it up
daily and, when being very busy, sometimes
hourly or even more often. (Why the fuck would I want to redo even an hour's worth of work, especially, when I'm in a hurry?!)