"Discredited old ones" like, say, Marxism?
Marxism is the strawman that the right wheels out to try and push back against policies that encourage equality. Equality doesn't equal marxism, proving marxism won't work doesn't prove that policies for equality won't work.
One point I concede to conservatives is that being too strict about equality dampens personal autonomy (which is very important to happiness) and reduces incentives to innovate. A balance must be found. I should note that happiness from autonomy follows an inverted U curve, where too much autonomy (e.g. too many choices) causes just as much unhappiness as too little. Additionally, many extremely wealthy people don't spend in proportion to their earnings, the money is just their score in the game of capitalism, so redistributing more of their earnings doesn't materially affect them as long as you are doing the same thing to their competitors. Based on these facts, I believe that the autonomy/equality balance is currently very sub-optimal in terms of happiness.
"Evidence" like, say, North Korea? Cambodia under Pol Pot? The Soviet Union under Stalin? Maoist China?
Heck, people are so happy with the equality in Cuba that they'll cross shark-infested waters in rafts they've made of trash bags stuffed with styrofoam packing peanuts.
I think your "fact" is not supported by the...err...facts.
One remaining difference was that Marxism was at least well-intentioned, whereas Ayn Rand basically turned enjoyment of other's suffering into a philosophy.
And, luckily, it seems we will be spared any attempts to implement Randian cruelty, since it has turned from an actual political force to no more than many people's college embarrassment, even in SV.
I'm no Randian by any means, but I'd still treat her ideas honestly. By your statement, you either haven't read her works, don't understand them, or understand them and you are simply being dishonest in your representation of them. In any case, her philosophy, whether it is correct or not, is not one that "turned enjoyment of other's suffering into a philosophy."
It turns out you can treat her Objectivist philosophy like any other philosophy and actually attack the premises of her arguments. Disagree with her supposed solution to the "is-ought" problem, fine, present an argument against it...in my opinion, that is a much better route to take than completely misrepresenting her philosophy.
Irrespective of what you think she said, her core point was that "If a man lives for anyone but himself, he will be a deeply, deeply sad man".
Ayn Rand herself get that question asked to her whenever she did something which your misconception about her idea would lead you to believe that it should be a contradiction by her philosophy to act in such a way. For instance she supported her husband's art venture for a while, and the interviewer asks her why would she do that, and she explains the same thing. [1]
Clearing of this misconception DOES NOT mean that you agree with her, I'm just saying that your point of disagreement isn't what you think it is.
Her philosophy doesn't think (which was made clear in Galt's speech) that a mother buying food for her kids by forgoing to not buy a fancy hat for herself is a 'sacrifice'. She values her children's wellbeing more than the hat.
The problem also does not come in when Bill Gates gives up majority of his wealth to a charity as long as he truly does want to do that. The problem comes in when society takes 99% of these 'non-sacrificial actions', creates a moral scale out of it and asks everyone to follow it.
It translates to two levels of action:
Individual level: "I don't really want to become a doctor but my mom and dad would get upset if I didn't so I will".
Societal level: "Sure you don't want to pay for poor people's healthcare because you'd rather buy an XBox, but you must make this sacrifice for society's sake".
Rand's core philosophy of Objectivism says that both these paths to individual (like Peter Keating in Fountainhead) and societal unhappiness (like any socialist/communist society out there).
Well, it claims to be. Others would say it's a stalking horse for grabbing power over other people.
Given the 100 million plus victims, I'd say that the latter is more likely to be the case.