> Suppose he gets hit by a car.
let's suppose he does. let's also suppose a probate lawyer will notify you that the principal of the firm you are working with has been killed, the company will go into receivership and run by an organization that specializes in that sort of thing until all the customers have been notified of the need to switch providers. then the assets will be liquidated, either by the estate or the government in lieu of an estate if there is no next of kin or trust / family / whatever.
suppose your large provider goes bankrupt and is bought out, and accidentally shuts off your fiber as part of the takeover process? what then? do you think anyone gives a shit about you then?
this has happened to me, personally. i have 3 internet connections at home for this reason (2 LTE lines and a cable line). in addition, i know _ALL_ the spots around my house where i can get a wifi signal. this is because i take my business seriously, like most people do. i don't expect some magic person to drop out of the sky during an emergency and fix everything for me.
my primary cable ISP is one of the largest in the nation, i'm not going to be fooled into thinking they're somehow reliable. they're never on time, and their service sucks. yet my plumbing company, owned/run by a single guy, always shows up on time and fixes my problem (i live in an old building with plumbing problems).
you live in a world of constant "what if" fear because you lack the experience to know how to handle bad business situations. a small business has more to fear from their customers simply not paying than from inability to deliver good service.