There are some stocks that you shouldn't bother investing in, even if it comes at no financial cost to you. There is always an opportunity cost to consider -- like earning a worse return as a result of making a poor investment decision. That's why regardless of how you accumulate money to invest with, you don't necessarily want to make reckless investing decisions.

A couple of stocks that look too risky to buy with even free money are Tilray Brands (TLRY -2.29%) and BlackBerry (BB -4.08%). Here's why you're better off avoiding these businesses.

1. Tilray Brands

Investing in cannabis is risky as it is, given the high level of competition in the growing industry. Generating consistent growth and profits is rare. And while Tilray's business has grown in the past year, that has been mainly due to its merger with low-cost marijuana producer Aphria, which closed in May 2021. But the cannabis company's top line has flattened recently and generating meaningful growth isn't likely going to be as easy anymore with an abundance of supply in the market.

TLRY Revenue (Quarterly) Chart

TLRY Revenue (Quarterly) data by YCharts

The company's bottom line is normally firmly in the red as well, with impairment charges on inventory, goodwill, and intangible assets in the fiscal fourth quarter (ending May 31) recently sending its net loss to a mammoth $457.8 million.

But underwhelming financials are just part of the reason why Tilray is a risky buy. I'd avoid the stock mainly because of the company's management, which looks to be overly bullish on the future, projecting annual revenue of $4 billion in just a few years (a big jump from the $628.4 million it reported in fiscal 2022). Another sign of its overconfidence is evident through it overstating its importance with respect to legalization in the Germany market. Tilray recently made a statement saying that it was involved in a roundtable there with the German government. That turned out to be a gross misstatement that the German government corrected in a press release.

If you're investing in a company whose management is misrepresenting its business to be bigger and better than it is, you're running the risk of it not meeting its aggressive forecasts and projections. Tilray falls into that category, and that's why it's a stock I wouldn't bother investing in. Through the first nine months of the year, the pot stock is down 61%, and it wouldn't surprise me if Tilray fell even further in value in the weeks and months ahead.

2. BlackBerry

Tech company BlackBerry hasn't fared as badly as Tilray, but its stock is also down 50% year to date. The problem with this business is it looks to perpetually be a work in progress. A decade ago, it was known for its popular mobile devices, but intense competition in that area led to the business refocusing and transitioning toward cybersecurity and offering enterprise solutions. There has been sufficient time for the company to pivot and start generating growth again -- but that simply hasn't happened.

BB Revenue (Quarterly) Chart

BB Revenue (Quarterly) data by YCharts

Last week, BlackBerry released its numbers for its latest quarter, the second quarter of fiscal 2023. Sales of $168 million were unchanged from the previous period. While its gross margin of 63% looked strong, that was negated by its high operating costs. The company's research and development and selling, general, and administrative expenses totaled $140 million for the period ending Aug. 31 and were more than BlackBerry's gross profit of $106 million.

The company has said all the right things in the past, which should have suggested that growth opportunities are on the horizon. Last year, it announced it was expanding its partnership with Chinese tech company Baidu and that BlackBerry's QNX operating system would be used in the company's autonomous driving platform. A few years earlier, in 2019, BlackBerry also announced the acquisition of Cylance, a cybersecurity company that utilizes artificial intelligence (AI), as BlackBerry said it was taking "a giant step forward toward our goal of being the world's largest and most trusted AI-cybersecurity company."

But those developments haven't been paying off, and it's uncertain if they ever will. Despite the glowing optimism from management, investors need to be mindful of what the results say today, and where BlackBerry is right now. Its track record for growth isn't impressive, especially as there has been a rise in remote work during the pandemic and when its core business, cybersecurity, should have been in high demand. However, last quarter, cybersecurity sales declined 8% year over year.

Without a growth catalyst likely to turn things around for BlackBerry anytime soon, this is a company that investors shouldn't waste their time on as there are better growth stocks to choose from.