This completely ignores the the cost of setting up your cloud VMs, cost of downtime if your Internet is down etc.
Sure an actual home server might be more expensive in electricty alone, but you can keep your VMs there 24/7 for not extra cost or hassle.
If it takes you a day a month to spin up new instances in extra dmin work, then that alone eats way morethan $5 saved in electricity.
Not to mention that you can actually own your server et etc...