Many companies and investors need to learn a crucial lesson: Becoming a market leader is easy, but staying one for a prolonged period of time? Not so much. Success brings about imitators. And competition can quickly eat into sales, market share and profits. Just look at the lousy earnings from Peloton\n \n (PTON) and Beyond Meat \n \n (BYND)for example. Both stocks plunged following their latest results. Some of Peloton’s problems are because more people seem to be willing to leave the house and hit the gym instead. Strong results from Planet Fitness\n \n (PLNT), which recently reported earnings that topped forecasts, show that Peloton has plenty of competition outside the home. But there are also cheaper bikes on the market from the likes of Bowflex, Echelon and NordicTrack. Competition has forced Peloton to cut prices, and investors aren’t happy: Peloton’s shares have plunged nearly 70% this year. Too much competition is rarely a good thing Beyond Meat also is running into trouble because a category it helped create has gone mainstream. Sure, there are concerns that plant-based proteins may be a fad and that demand has peaked. But a bigger issue is the ubiquity of “fake meat” at restaurants and grocery stores. It’s no longer hard to find a good plant-based burger. And now, rival Impossible has distribution agreements with many big supermarket chains. So consumers no longer have just Beyond products as an option when looking to buy meatless burgers or nuggets. Traditional food companies like Kellogg\n \n (K), Tyson\n \n (TSN) and Hormel\n \n (HRL) have launched their own plant-based offerings too. It’s no wonder that Beyond Meat’s stock has lost nearly a third of its value this year. Meanwhile, mattress maker Casper\n \n (CSPR) has also found that it needed to do more than just advertise aggressively to capture share in a crowded market. The company was one of the pioneers of the mattress in a box business, and in 2019 it seemingly bought up ad space on every subway car in New York City. But competition from other upstarts like Purple\n \n (PRPL) and Leesa and established bedding companies Tempur Sealy\n \n (TPX) and Sleep Numbe\n \n (SNBR)r made life difficult for Casper -— so much so that Casper announced Monday it will be purchased by a private equity firm just 21 months after going public. Even though Casper shares nearly doubled Monday, the stock is still trading nearly 50% below its initial public offering price. Tough competition isn’t just an issue for early pioneers of an industry. For example, Disney\n \n (DIS) was by no means first to streaming media. But it quickly attracted subscribers and buzz away from Netflix\n \n (NFLX) when it launched with a stacked library of classic content and new shows like “The Mandalorian,” “WandaVision” and “Loki.” Netflix, as well as streaming rivals from Apple\n \n (AAPL) and Amazon\n \n (AMZN) and WarnerMedia’s HBO Max, have fought back though, often with edgier and more adult-oriented content like “Squid Game,” “Ted Lasso” and “The Flight Attendant.” (AT&T’s\n \n (T) WarnerMedia also owns CNN.) That has hurt Disney. The stock plunged earlier this month after reporting slower-than-expected subscriber growth for Disney+. All this shows just how hard it is to remain a market leader for an indefinite period of time without attracting competition that’s going to make life more difficult. In another example, just look at how Elon Musk’s Tesla\n \n (TSLA) has disrupted an entire industry. Entrenched auto giants GM\n \n (GM) and Ford\n \n (F) are now worth fractions of Tesla\n \n (TSLA)’s market value. Companies like Google owner Alphabet\n \n (GOOGL), Amazon, Facebook parent Meta Platforms\n \n (FB) and Apple are a few of the rare cases of industry leaders who have largely held onto and strengthened their market leads in their respective industries. But they are the exceptions, not the rule.