Then Raspberry Pi 0 is better option, it's only $5 & still good enough to run full node.
Sure, but Pi4 means you can run extra stuff in addition to a Bitcoin node
24/7/365 you could have running:
- private Email
- private social media
- lightning node
- personal dropbox
- sell stuff on openbazaar
- trade coins on Bisq
- remote control of anything on your home network (tell your robot butler to start cooking, turn the lights on and off to thwart burglars, etc
)
The list of things to do gets bigger, computing boards keep getting more powerful, and the Bitcoin devs keep reducing the resources needed to run Bitcoin (except disk space, of course)