Let's assume we have a) $5000 b) $10000 c) $15000 to invest, what do you suggest?
Since you asked this question in a Bitcoin discussion, perhaps you would choose to invest in Bitcoin if you had that kind of money. And I think it is a good plan or choice if you choose Bitcoin to invest in, and do it for the long term.
But first you have to learn and understand Bitcoin, especially regarding the risks involved, especially as Bitcoin is very volatile, and you also have to know your finances, whether you have a fixed income other than these funds. If not, you should not invest all your money and should divide it according to your needs or create a business so that you have a steady income to continue investing in Bitcoin regularly and can also meet your essential needs.
Don't be tempted to make big profits from Bitcoin, especially because of FOMO seeing that Bitcoin prices are bullish. It's best for you to learn about Bitcoin as a whole first so you don't regret it later.