i recently returned to roblox 15 years or so after playing it last (when it was still legos-but-on-the-computer) to play games with my nieces (who live far away)
here are my observations so far:
all games on roblox are, theoretically, free-to-play, but the moment you launch any game, you are inundated with pop-ups telling you to spend real world money
games on roblox physically section off entire areas of the game if you do not pay for a VIP pass (such as Dress To Impress)
games on roblox will place objects near to you so you will click on them assuming they are part of the baseline experience, only to have a pop-up that says "to use this item, pay real world money" (such as Animal Hospital Anomaly)
games on roblox will prompt you to pay money if you die so that you can continue playing that session of the game (such as 99 Nights In The Forest)
most avatar cosmetics on roblox cost some amount of money (with the lowest being the equivalent of real-world 5 US cents). the baseline cosmetics roblox provides you with are intentionally ugly/uncanny valley. when you dress your avatar and have you inventory open, there are ads directly below your owned items - both to serve as a "wouldn't you rather pay to have better items?" as well as to trick younger kids into thinking they already own those items, clicking on them, and buying them
most of the cosmetics (and games. and everything) on roblox are designed by players, not the company itself. these designers (from what i've read) are massively exploited and underpaid, and a lot of them are minors.
these items are called UGC (user generated content) and there's an entire market into tricking children into thinking they can receive UGC for free. they'll call a game "free UGC" or something and then present the user with three options: to remain AFK for several days in a row as they slowly accumulate one point at a time (which can then be turned in for a second fake currency for a terrible rate, like 100,000 points to 1 ticket), to play mini games on the server that are extremely difficult/time-consuming/have a low point payout, or to spend real world money to purchase fake currency to redeem the items. in all cases, the goal is to trick the child into remaining on the server for a long time (which results in payment from the roblox corporation for having an "active server") and/or to spend real world money directly - far more real world money than they would ever need to spend if they were to buy these items directly from the marketplace.
there's also an aftermarket for UGCs. because false scarcity is in play - "only x amount of this item exists." once acquired, they can be resold at a steep increase depending on perceived desirability and rarity. so people have bots in these servers (and elsewhere) mass-buying the UGC when the price is low, and reselling it for profit. preventing real human users from ever having access to them.
there's a server for UGC's where the entire premise is that you enter a promocode to give you the chance to buy the UGC... not get it automatically for free. in order to get the chance to buy, you often have to "follow" or "friend" content creators, join groups, or have previously purchased specific items. this server is called "Free UGC Codes" btw. to, again, trick children into thinking they will get these items for free, seeing the requirements, making other purchases and following people, only to be met with another payment screen, and decide to click on it anyway because "it really isn't that much money" and "i already put in so much effort."
there are very few genuinely free items you can acquire. they are often not worth it. i spent approximately 2 hours playing a cookie-clicker-style hair salon tycoon where i had to keep building facilities by raising (in game) money and walking on top of buttons. it was an incredibly tedious experience designed to keep me (and any kids) on that server for as long as possible. i got my hot pink headphones, butterfly wings, and multicolored hair, but at what cost? my time and frustration.
there are probably more aspects of roblox's economy i haven't encountered yet, but this is what i've seen after about 4 days or so.
yousharknotpass
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vaporwave
theartofmadeline
