The same thing applies, you have to buy/power GPUs and decide they are best utilised mining ethereum, mining another coin or powering your new startup.

You're right and it's proven pretty robust at that. This is a good proof of work, because it means that anyone with commodity hardware can set up a miner, and the playing field is pretty level.

Assuming everyone has existing funds to acquire mining hardware.

Large existing expendable cash has a greater advantage to mine and mint. Mining pool operators are also in a position to manipulate minting and transactions in the network.