What makes markets continue to climb to record highs and why don't they crash anymore, is the simple answer R&D?

This is just a shower thought for discussion. Historically a company would do the same thing over and over and not devote anything to R&D this meant when a new company opened with a new version the old company would dramatically crash and shake up the market. Modern companies are now so future proof that they devote tens of billions into R&D (including buying out companies) the result is new avenues of income every year, Microsoft is a great example; started as basic software, went on to cloud services, ERP, CRM and now AI solutions. Just think of any tech company what they started with and what they now offer. A bit tired of people saying we are due a crash soon! And they will say AI is the same as the .com bubble, but those companies that crashed are now some of the most valuable in the world... I'm not going to sell my stock in xyz company because it could be the next smartphone company or website company that grows 5000% because there is currently zero market saturation. For the market to go down you would need to have no R&D happening, no promise of crazy future earning potential, you'd need a very boring and quiet climate with nothing happening?