It's more of don't keep all eggs in a single basket. Diversify!
Try to avoid having more than 60% your customers from a single geography or industry (just like your financial investments - diversify). On the similar lines, don't depend on that single customer that generates most of the revenue. If it goes, all your strategy would go for a toss.
Delight your current customers that you're irreplaceable for them - be more than just a vendor/provider.
Diversify your source of leads. Don't depend just a single source of lead generation and ignoring others (e.g. focusing on Outbound and ignoring inbound/networking)
Keep up with what's in the market and where things are going (e.g. ChatGPT had big impact on few profiles/industry). Instead of seeing it as threat, take it as opportunity to improve your product or skills.