I'm tech support so I've seen some stuff, sooo many intranet sites on internal servers don't have HTTPS, almost only the stuff built to be accessible from the outside has it. Anything important with automatic login could be spoofed if the attacker knows the address and protocol (which is likely to leak as soon as the DHCP hijack is applied, as the browser continues to send requests to these intranet sites until it times out). Plaintext session cookies are also really easy to steal this way.
Chrome has a setting which I bet many orgs have a policy for;
https://chromeenterprise.google/policies/#OverrideSecurityRestrictionsOnInsecureOrigin
Of course they should set up TLS terminators in front of anything which doesn't support TLS directly, but they won't get that done for everything
Keep in mind that because few residential users max out capacity simultaneously the ISPs "overbook" capacity, and usually this works out because they have solid stats on average use and usually few people need the max capacity simultaneously.
Of course some ISPs are greedier than others and do it to the extreme where the uplink/downlink is regularly maxed out without giving anything near the promised bandwidth to a significant fraction of customers. The latter part should be disincentivized.
Force the ISPs to keep stats on peak load and how frequently their customers are unable to get advertised bandwidth, and if it's above some threshold it should be considered comparable to excess downtime, and then they should be forced to pay back the affected customers. The only way they can avoid losing money is by either changing their plans to make a realistic offer or by building out capacity.