I'd argue it's susceptible to 51% attack already, but as BTC's value grows, the profitability from pulling off a 51% grows as well. Therefore, the hashrate not

I'd argue it's susceptible to 51% attack already, but as BTC's value grows, the profitability from pulling off a 51% grows as well. Therefore, the hashrate not scaling with the market cap of BTC makes the prospect of funding a 51% attack more and more appealing.