As I commented on their Facebook page earlier in the month.
If you want to sell me 5G, then you need to cater to both phones and mobile broadband dongles that you sell.
I can buy a phone with them, and put a SIM in, and share out a 100Gb data plan for much less than the cost of buying a contract sim, sticking it into a 4G Wifi box (that they also sell) and offering that connection out directly over Wifi as my primary Internet connection - which is limited to 40Gb max on their mobile broadband plans and 9Gb if you try to "mis-use" a phone plan to do it.
Who's going to use more traffic? Who's more likely to want 5G speeds? Who's going to pay more for it? Who's more likely to actually achieve top speed and look good on your data? Someone with an iPhone? Or someone who bought a mobile broadband SIM for a mobile broadband box that they sell themselves, with a huge feck-off antenna, and who uses every Gb of data every month as they don't use any other Internet connection?
I get great speed, great coverage, and pathetic amounts of data - I literally can't even up it, in any way, shape or form, to 50Gb, 60Gb, 100Gb, or beyond. So why would I touch a 5G SIM with them? And how is someone using 100Gb of iPhone data roaming damn well everywhere any worse for you than me sitting here and using 100Gb of data on one of your SIMs in a fixed place?
Cater to the market that WANTS to burn data, WANTS to pay you for it, WANTS the higher speeds and can use them, and WANTS as little from you as possible (just gimme data, I don't care about voice, text, etc. as I can't even use them anyway!).
Literally, scale the existing 40Gb / £30 up and allow me to buy that and I'll be happy. Other providers allow me to go to ridiculous allowances for stupid money, but that's not even an option.
And why are we still treating "tethering" clients as second-class citizens when you're actually producing a SIM designed especially for them, and selling devices especially for that?