The concept of "cutting your coat according to the cloth" has long gone. (Though possibly will be coming back)
I was brought up by parents brought up during the war. They were brought up by parents born in the 1890s early 1900s. (My grandmother lost her first sweetheart in WW1 so was older when having children, both my mum and I were older first time parents) It was all save up, make do and mend etc. Traditional working class clear memories of no NHS, little support, living in homes with no indoor plumbing. (Bad enough to get put in the first council houses in the village, considered poor housing in the thirties, outside pump for water and privy at the end of the garden)
Things changed in the '80s with access to credit. Attitudes changed. Generations were far enough away from hardship to not remember. Welfare state, baby boomers, free uni education for many with grants, vaccinations for childhood illnesses, All bloody good stuff but a lot of people lost the wariness of spending more than they could afford etc.
Sadly things have got tough again. (Bad time in the nineties, but some recovery til 2008 when finances are tough again) But people have been brought up by parents and grandparents born and raised in the better times of more generous welfare state etc advertising of having it all (on credit) things continually getting better... Secure employment. instant gratification, poor teaching on budgeting society is not scared of debt.
Living within your means is harder in our society that pushes credit and spending and low interest rates on savings. Just as eating healthily is harder with readily available prepared food and both parents needing to work. It's easier to see what other people have got and want it and harder to resist. Pets are on every other advert. Loads of people have a dog it's seen as normal.
What is a luxury has changed. Past generation luxuries are now basics. Things that were luxuries are now essential in our society. (Smart phone for example as everything has gone online digital) some people need cars as public transport has declined, got expensive and jobs have moved out of the city where people live.
To me, pets are an expensive luxury. To others, not so much. Especially if they had them before their circumstances changed.