Asking if you should buy a game now or wait for a sale isn't allowed, asking when a game will go on sale is not allowed, asking how big of a discount a game might get is not allowed. Use SteamDB to look at sale histories on games. Source: 6 months ago

Here's how to cure you from your buying habit, checkout https://steamdb.info/, check the price history of the game you're thinking of getting. Most likely it's on sale once every odd month, and discount percentages are only ever increasing over time. So really you can just buy it when you think you have time to play it soon. Source: 6 months ago

Correct, it's trending on https://steamdb.info/ if you look at the panel, some games will show zero players. But OP is wrong, other games are trending too. Source: 6 months ago

Asking if you should buy a game now or wait for a sale isn't allowed & asking when a game will go on sale is not allowed. Use SteamDB to look at sale histories on games. Source: 6 months ago

You can use the Steam console to download older versions as described here. You can get the depot and manifest IDs from SteamDB. Source: 6 months ago

I also assume you're new to PC, so if you are, you can get amazing deals on games via bundle sites, such as Humble Bundle, Fanatical, GreenManGaming, and etc as they sell game keys you can redeem via Epic, Steam, or etc... Most game keys are for Steam. Can use tool site to help find best deal on games isthereanydeal.com, please note games do go on sale, so don't be scared off by games full price tag as those are... Source: almost 3 years ago

For cheap games, depends what games you want to look for, action, fighting, racing, what you looking for? There's also bundle sites that sell bunch of games for low price which are mostly sold Steam keys, which you can redeem on Steam. Such as humble bundle, fanatical, indie gala, or etc... Can use site like isthereanydeal.com to look for certain game deals as well. Source: about 3 years ago