Nations sometimes do launch invasions that have no military chance of success.
Just look at the Argentine invasion of the Falklands in the 1980s.
Hmh? It was the British retaking of the islands that had virtually no chance of success. Thatcher decided to attempt anyway; had she faced that invasion just twelve months later, Britain would certainly have lost the islands, as the Royal Navy would no longer have had amphibious warfare vessels capable of operating across two oceans.
It was Argentina that had virtually no chance of success. Because
1) Their military was little more than an internal police force which had spent a decade torturing and murdering people inside Argentina itself.
2) Argentina figured the British would not fight and made no preparations for the British retaking the islands. Argentina knew that if the British fought, that Argentina would lose.
Especially as it was an unspoken truth that if the British got in trouble, the U.S. would send a carrier battle group and win the war for them.