Never invest more than you can afford to lose. Stocks are not like money in the bank. You can invest $5000 today, and have it drop to $3000 in a few weeks. And in some cases, the $3000 will never get back to the $5000 you started with (been there, done that). Still, stocks should be a part of your investment mix. Figure on 20% of your assets, not more. The bulk of your $ should be in a bank where its safe. (unless you’re talking about 6-7 figures, in which case you need a proffesional money manager)
Also consider buying a mutual fund instead of a particular stock. In the 80s, almost stock you touched turned to gold. Not so easily done in today’s market.