Even 1tb SSD is cheap, just use QLC ssd to save money they have have good tb per dollar ratio.
The problem is always internet connection. Some people have limited budget but nowadays they can always use starlink.
The $100 cost per year is for internet probably. People back then can run full node, people today can run it cheaper.
I don't think there is any plan on starlink with $100/yearly plan, even in a third world country where they are currently doing some bonanza to entice people to buy their services offers two plan, the residential plan and business plan. The business plan is between range of $98-$100 a month while the residential plan goes for $40 and above varying on how the rate changes, they sometimes cap the download speed when you reach a certain download to terabyte on the residential plan.
I honestly think, with or without Bitcoin node you can still own a bitcoin
The point isn't about having Bitcoin but having the best way to spend it, receive it and use it to your own taste, you don't have to depend on any third party node to broadcast your transaction where they get to monitor your IP address and wallet address. With your own node, you don't have to trust anyone but verify every transaction that comes to your wallet. You also support the network when you run node and make transaction even more decentralized.