You understand there's over 13,000 cryptocurrencies, right? Your broad statement here is no different from stereotyping someone based on physical appearance. How many whitepapers, aka detailed business plans for coins, have you read? There are always scammers online, in every industry, across the board. But while there are many bullshit coins, there's still unquestionably very solid options.
For example, BTC has no website, no office, no owner, and is fully decentralized. Other examples of decentralized coins include ETH, XMR, ZEC, LINK, DAI, GRT, AAVE, INJ, and MKR to name a few. It's a great practice to research and analyze data before making a statement on topics you're unfamiliar with, but to each their own.
Ever pop your ears when going up a mountain or during flight? This is air pressure changes. Either way, water tight does not mean air tight, while air tight does mean water tight assuming the material is not water soluble.