For a man who has lived well within his means for much of his adult life Walt really does start living excessively by the time he actually starts making serious money in season 4. But can any of us say we wouldn't do the same? For much of the first three seasons Walt is forced to use what little money he has (little by drug lord standards anyway) on medical treatments for himself and then his brother-in-law, which leaves very little for so-called luxuries. Once Skyler outs Walt as a man with a serious gambling problem which has made him incredibly rich he sees it as an opportunity to splash out a little, but perhaps buying himself and irritating son Walt Jr. muscle cars that would look incredibly out of place to the White's neighbours, not to mention the taxman who knows nothing about Walt's fictional casino winnings. It's this kind of gluttonous excess that illustrated to us at home that the Walter White we once knew was no more and the transformation into his new alter-ego was nearing completion.
