Everything you've written has been opposed at some point in this thread. A high-cost program like this is an unfortunate expenditure and what you get with multi-service demands, but that's the price of keeping an edge. If you consider inflation and the mass of aircraft this jet is designed to replace, it's not that shocking.
The CAS argument is more complex than you make it. The F-35 would be able to provide support where the A-10 could not. The reality is that survival of the A-10 is questionable in a battlefield filled with modern air defenses. Even if the 30mm gun provides very direct and predictable fire, small PGMs can suffice in most situations, and they'll have to do because we can't keep the A-10 around indefinitely. I think everyone agrees that it will leave a hole in the US inventory. Small, inexpensive CAS platforms might one day fill that void, but the A-10 is a purpose-built Cold War aircraft that we cannot expect to use forever.
In the end, as an American, I want a military that is capable of defending against and striking modern threats, not one that happens to be great for CAS in a medieval desert country. (Caliphate?)
PS. Please capitalize, your post is hard to read.