Tech companies can never rest on their laurels. Technological advancement and disruption are ever-present in the technology sector, and even the most successful tech companies face the constant threat of being left behind. The history of the tech industry is a graveyard of once-promising companies that failed to adapt to a changing world.

Technology is a volatile and messy business, and for investors, avoiding the losers can be just as important as picking the winners. While dramatic turnarounds can certainly happen, with a company on the path to failure reinventing itself and finding success anew, betting on long shots is more often than not a bad idea. With that in mind, here are three struggling tech companies that, according to our Foolish contributors, may not ultimately survive.

Andres Cardenal: BlackBerry(NYSE:BB)is scheduled to report earnings on Friday, Sept. 25. This report will provide an opportunity for investors to take a fresh look at the company's financials, but the main trends have been notoriously weak over the past several years.

BlackBerry reported $19.9 billion in revenue during the fiscal year ended in February 2011. Fast forward five years, and Wall Street analysts are expecting the company to deliver $2.5 billion in sales during the year ending February 2016.

The company produced $123 million in free cash flow last quarter, and the balance sheet has more cash and financial investments than debt. Total cash, cash equivalents, and short and long-term investments amounted to $3.32 billion as of May 30. Deducting $1.25 billion in debt, this still leaves BlackBerry with a net cash balance of $2.07 billion as of the end of the last quarter. Financial risk seems to be contained for the time being, but it's hard to tell for how long the company can avoid financial trouble if sales continue declining.

BlackBerry is betting on software to turn things around, particularly focusing on the enterprise mobility management space. This sounds like a smart move from management, but transformations are seldom easy to implement, and BlackBerry remains a remarkably risky investment at this stage.

Tim Green: Advanced Micro Devices (NASDAQ:AMD)has seen its share of both the CPU and GPU markets collapse over the past few years. The company has been slashing research and development spending as revenue has declined, and the once-profitable business has now reported a string of big losses. During the second quarter, AMD reported a net loss of $181 million, with sales slumping 35% year-over-year.

Deep problems plague the company. AMD CPUs can't match Intel in terms of performance, and the recent weakness in the PC market has put even more pressure on AMD's core business. In the discrete GPU market, AMD has been bleeding share to NVIDIA for the past year. During the second quarter, AMD shipped just 18% of discrete GPUs, down from about 40% during the second quarter of 2014. AMD's computing and graphics segment, which includes both CPUs and GPUs, reported a 54% year-over-year decline in revenue during the second quarter, and the only thing keeping the company afloat are sales of chips that go into game consoles.

AMD has enough cash, about $829 million, to keep going for a while, but with $2.2 billion of debt and no sign that these losses will let up anytime soon, a turnaround is looking increasingly remote with each passing quarter. The launch of new CPU chips based on the Zen architecture, planned for next year, is AMD's best chance at reversing the troubling trends plaguing its business. But Zen looks to be a Hail Mary for AMD; anything short of perfection may not be enough to save the company.

Steve Symington: Groupon (NASDAQ:GRPN)shares have fallen more than 80% since its IPO in 2011, including a nearly 50% decline year-to-date. Though the online daily deals specialist still hopes to become a driving force in e-commerce, its most recent quarterly report saw Groupon not only fall short of analyst expectations for both revenue (up just 3% to $738.4 million) and adjusted earnings ($13.8 million, or $0.02 per share), but also reduce its full-year guidance for adjusted EBITDA by more than $25 million to $290 million. And though Groupon did achieve a quarterly GAAP net profit of $109.1 million, or $0.16 per share, that included a $0.21 per share gain from the sale of Ticket Monster, a Korean e-commerce company it incidentally acquired to propel international growth less than two years ago.

To be fair, Groupon would have achieved a more impressive 11% top line increase had it not been for the effects of foreign exchange. But the fact remains Groupon's revenue growth has largely stalled since it began selling physical goods in 2013 -- a move that bolstered sales at the time but came at the expense of previously cushy margins. And though Groupon hopes to make waves with the recent launch of its "Groupon To Go" food delivery service -- which offers up to 10% off every order and, according to management, expands its reach into a new $70 billion market -- it will need to displace entrenched competitors in the space like Seamless and GrubHub in the process. In the end, if Groupon's efforts to diversify here fail as the rest of the business stalls, I fear the stock will only continue its downward spiral.