Individual users running massscan et al, are not going to produce anything like the level of traffic all the major providers (and quite a few sitest that aren't

Individual users running massscan et al, are not going to produce anything like the level of traffic all the major providers (and quite a few sitest that aren't that large) see from DDoS attacks on a pretty regular basis. Given that there are several sites who scan the Internet regularly for more than just open ports (e.g. Shodan, Binary Edge, Censys) it's not a volume of traffic that should cause a concern.