Just out of interest, is there anybody posting on this thread who is actually an expert in something related to this, eg. Transport Planner, Engineer, Economist, Traffic Modeller?
The Channel Tunnel was a disaster from an economics perspective. It opened a year late and its costs spiraled from an estimated £4.9bn in 1987 to £10.5bn in 1994, due to increased tunneling, rolling stock, and financing costs. At today's prices that's about £25bn. It is unlikely the British government would put up any of this - they didn't for the Channel Tunnel. No private investor would touch it either. (Oh also, the Bering Strait tunnel hasn't been built yet, and probably won't ever be. $10bn for that is a laughable Russian estimate to try to get the US on board - the same US where the closest thing to high-speed rail is a plan for a train from Las Vegas to somewhere in the Californian desert.)
Revenues and passenger numbers were far below those which were expected. Eurotunnel Group had to be restructured twice and several billion pounds of its debt were written off by the investment banks underwriting it. Projected passenger figures for 2003 were 2.8m. They were actually 1.4m. Bear in mind the cross-Channel passenger market was 32m in 1994 (don't have updated figures but the increase would have been very gradual). This was greater than the entire market between Ireland and Britain today. Of that market, only Dublin-London/Manchester/Birmingham would be competitive with air travel, and when the average fare from Dublin to London is already just €40 (and you're basing your revenue estimations on an average fare of €50?!), the economies of scale needed to make a train operation viable would be abortive.
Listen mate, an Irish Sea tunnel is a lovely dream but it's nothing more than that. It's nice to be optimistic but you need to cop on and put this idea to bed. It will never, ever happen in my lifetime nor yours.