I'm not getting into this "different generation" thing, because my FIL would be 83 right now, and he was the biggest lying spendthrift around, and his father gambled their money away so that FIL had to work when he was 6 years old (selling newspapers). It's not a generational thing, it's a human thing.
But anyway.
My MIL goes on about things like that too, and we ignore her. If she gets on our cases about things, we stop visiting. We tried to give her alone time with DS for the first time in 2 years (when she ruined it by having a friend over and they spoke their native language the whole time, and DS doesn't know the language, and he felt sad), and she ruined that visit too. DS was made to feel sad and bad by his grandmother, and doesn't want to see her "until college" (he's 6).
Anyway, don't let her go on about it. YOu seem to be doing just fine, and as you said, she had a beach house, which had to cost some money to buy and keep up over the years...it's not like she took NO vacations.
She's very lucky that when she was ready to travel, she could. My MIL waited and waited and waited until her husband retired. after the third retirement (they had never lived together more than 3 months at a time, thanks to Navy, Merchant Marines, and private shipping companies, so he'd get home and inside a month he was looking for a new job) it finally "stuck", and then a year later he was dead. Having not filed taxes for 6 years (lying to MIL while doing turbotax which only requires signatures the first year). And now she lives on his pension, widow's SS, and gets to pay the IRS 50K back....no traveling for her, except for what her children provide her with (she doesn't complain about THAT, by the way).
Your MIL can have her opinions, but she doesn't get to ruin the fun of other people, especially when those people are doing just fine.