Yes the 'hard work', ignoring luck line is obnoxious, always.
That doesn't remove the social, even moral duty to enjoy your good fortune with good grace, to show appreciation and gratitude, however it was accumulated.
Imagine being less well off and really, really wanting to make enough money, somehow, to afford nice handbags, clothes and holidays. Thinking about how much you would enjoy those things. Maybe entering competitions, buying lottery tickets, in the hope of winning them.
Then you meet up with your better-off relatives, who have many of the things you long for. You admire their lovely handbag and holiday, thinking about how wonderful it must be to have these things. Instead of saying 'well thank you, it is wonderful isn't it, I'm very lucky', they pretend not to have the lovely thing, blatantly lie about it, say they don't enjoy it very much anyway, pretend the very desirable holiday is affordable to just about anyone who cuts out a few coupons.
What a horrible slap in the face. If they despise their own good fortune so much, why don't they give it away to someone who would appreciate it?
I know that isn't OP's situation exactly, in terms of her family background. But it is a normal situation, where a less well off person admires a better off person's lovely things.
As for OP, isn't it time to allow yourself a bit of a gloat over your unpleasant sister? Yes you do have the nice things and she cannot steal them any more. Following the generally acceptable 'gracious enjoyment' line will do you no harm.