Over the long run, the primary driver of a stock's market value appreciation is the growth in its underlying intrinsic value, specifically its earnings per share (EPS). This simple but profound concept grounds investing in business fundamentals, treating stocks as ownership stakes rather than speculative tickers.

Counter to conventional value investing wisdom, a low Price-to-Earnings (P/E) ratio is often a "value trap" that exists for a valid, negative reason. A high P/E, conversely, is a more reliable indicator that a stock may be overvalued and worth selling. This suggests avoiding cheap stocks is more important than simply finding them.

The belief that 'any sale is better than no sale' is dangerous. When your revenue is less than the direct cost of sales (negative margins), each transaction compounds your losses. It is strategically better to make no sale than a negative-margin one.

Aggregate profitability can mask serious issues. A company's positive bottom line might be propped up by one highly profitable offer while another "bestseller" is actually losing money on every sale. This requires a granular, per-product profitability analysis to uncover.

WeWork created "Community Adjusted EBITDA," a metric that conveniently excluded core costs like rent and salaries. This farcical KPI incentivized top-line growth at any cost, masking massive unprofitability and ultimately destroying shareholder value. Be wary of overly creative accounting.

Instead of labeling a potential issue like negative cash flow as a definitive "red flag," which can be misleading, view it as a "flammable item." By itself, it may be harmless. The real danger only materializes when a "spark"—a catalyst like a new competitor or rising interest rates—is introduced.

A profitable P&L can mask imminent death. A big contract booked as revenue makes you feel rich on paper, while you're actually one payroll cycle from insolvency. The only true survival metric is a rolling 13-week cash flow document, updated weekly, showing actual cash in and cash out.

The industry glorifies aggressive revenue growth, but scaling an unprofitable model is a trap. If a business isn't profitable at $1 million, it will only amplify its losses at $5 million. Sustainable growth requires a strong financial foundation and a focus on the bottom line, not just the top.

Companies reporting losses under GAAP rules aren't always bad investments. If losses stem from expensing intangible investments like R&D, they are 'GAP losers' with strong economics. Historically, this cohort has delivered higher returns than both consistently profitable companies and 'real losers'.