Profit drops faster than revenue if your costs are more than zero. This is always true no matter what you are talking about.
For instance if you have $5 in electricity costs, and your revenue goes from $12 to $6, your revenue dropped by 50% ($12 to $6), but profits went from $7 to $1, a drop of more than 85%.
Price drives difficulty, not the other way around. This has been debated for years now and it's true: higher prices get miners excited and they plow resources into mining, thus driving up difficulty. Rising difficulty does not by itself push up prices. If there is a huge disconnect then maybe some people stop buying coins directly and buy mining rigs instead, but otherwise, price is a function of supply and demand. Demand is generated from enthusiastic users/speculators/etc. and supply is fixed at 7200 (now 3600) coins per day. It doesn't matter if there is one miner or one million miners, only 3600 coins are produced per day. Furthermore 3600 coins is just a tiny drop in the bucket; over 11 million bitcoins have already been mined. So each day's mining doesn't materially impact supply.
Short story is that higher prices leads to higher difficulty, but higher difficulty does not necessarily lead to higher prices.