Values start to have costs only when they are realized or implemented.

How? Are you saying that I might hold legitimate value in something, but be worse off if I get it?

Costlessly increasing the welfare of strangers doesn't sound like altruism to me.

OK, so we are having a dictionary writers' dispute - one I don't especially care to continue. So every place I used 'altruism,' substitute 'being decent' or 'being a good egg,' or whatever. (Please check, though, that your usage is somewhat consistent.)

But your initial claim (the one that I initially challenged) was that rationality has nothing to do with value, and is manifestly false.