Problem - Solving non-real problem
Market size - Too small, too cheap, too competitive
Product - no P/M fit, product quality
Marketing Channel - no low cost marketing channel to reach bulk customers, CAC way high than revenue, Product positioning and differentiation iissues
Pricing - Too high hence unaffordable, too low hence cheap quality perception issue, no/low profitability
Offer - No/low persuasion
Team - Co-founder, Hiring/firing issues of team members
Finance - Funding, cash flow problems
Competition - More funded, more resourceful to copy your competitive features over night, stealing team members with more money
Timing - Too late or too early in the market
What else? pls add more for the benefit of the community.