Golem plays a Hoard and has $6 to spend. It wants to buy a Gold. It doesn't recognize that it would be better to buy a Duchy and get a free Gold.
Golem plays a Goons and has $6 to spend. It wants to buy another Goons, with Goons+Copper not too far behind. If it knew it would get 1 VP more, it would certainly chose Goons+Copper.
Golem plays a Hoard and has $6 to spend. It wants to buy a Gold. It doesn't recognize that it would be better to buy a Duchy and get a free Gold.
Golem plays a Goons and has $6 to spend. It wants to buy another Goons, with Goons+Copper not too far behind. If it knew it would get 1 VP more, it would certainly chose Goons+Copper.