No that's not true. There's plenty left to mine in Bitcoin alone, the rewards get less and less as it gets closer to the max supply so it slows down more and more. Also lots to mine in other major cryptos. Also there are constantly new coins being created and many of them are mineable. The only way that mining will end is if, one day down the line, the only cryptos people use are not mineable but instead their networks operate on different models such as proof of stake (PoS) or proof of work (PoW) or something else which may not even be invented yet.
With crypto you can't believe anything you read. I mean some stuff you read is true but you have to do your own research because basically the entire market is being manipulated at a very high level with cycles of articles and even mainstream "news" alternating between causing fear, uncertainty and doubt, which gets people to sell, bringing the price down. Then the people with massive amounts of money who are doing the manipulating will buy a lot of it at a low price, which spikes the price up. Then you'll see articles about how "you have to buy this or that before it's too late, DON'T MISS OUT!!1!!1", and that coupled with the sudden price spiking gets people to buy, and then once the price spikes up to a certain point the price manipulators sell it all for a tidy profit and the people who bought on the spike lose out.
Crypto is in its really early stages, it hasn't even been adopted into our technology much at all yet. People are working on that though. Right now it's still an unregulated market so there is nothing stopping massive price manipulation which is basically stalling the market out right now and scaring more and more investors off. As much as I like the idea of an unregulated market, I think market regulations are necessary to stabilize things and make crypto seem like something legitimate to the wider world and business investors. Also, once the technology is developed to the point that it gets adopted widely into processes that are integral to our societies, we'll realize that even though we're in a crypto bubble at the moment, years from now it will be much bigger than it has ever been so far, and the utility of the technology will be self-evident (right now, although there are great cryptos with working products that go far beyond currency applications, the market is driven almost entirely by speculation). It's just like the dot com bubble... many companies didn't do anything and a lot of people made tons of money because of the hype of this new technology, the Internet. Lots of people said it wasn't going to last. But of course now we realize how much the Internet has fundamentally changed so much, and though the bubble burst, from it emerged some of the biggest companies in the world, like Amazon, Google, and so on. And the people who held on through the bubble bursting, who bought Amazon or Google stocks, have seen a tremendous growth from their investment, even well beyond what it was at the height of the bubble.
I bought in like half of my investment basically at the height of the price spike in late December, which sucks because I'm well in the negative now. But looking back years from now, this will just be a bump. Or so I believe.