I was willing to invest into S&P500 index but cannot find any platform without a huge leverage (for example iqOption, plus500 have leverage of 1:20 which makes usually safe investment become extremely risky (already lost some money because of that)). Are there platforms that allow to invest into S&P500 without leverage?
Member mhoran's comment was an answer.
why not just invest with any of the dozens of mutual fund companies that have an S&P 500 index fund or ETF?
The ETFs are more commonly not leveraged. Of course, some are, so you'll avoid those. But the ticker SPY is the most popular one and it reflects no leverage at all. You get the return of the S&P less a tiny expense. Note, you don't offer a country tag, so we don't know what's available to you.
I don't think you've been buying index funds
I'm noting what they say on their website:
CFDs are complex instruments and come with a high risk of losing money rapidly due to leverage. 77% of retail investor accounts lose money when trading CFDs with this provider. You should consider whether you understand how CFDs work and whether you can afford to take the high risk of losing your money.
We know that's not an index fund. If I opened 100 accounts at different times and invested them in index funds such as VFINX, VTI, VOO, etc., we can safely say 77 of them would not lose money.
These look like derivatives
... which are a heck of a lot more than merely "leveraged". Specifically CFD -- though the very name of the Web site includes the word "option", so their products are derivatives through and through.
You know of course that volatility is a normal component of investments, and volatility and growth go hand in hand. That makes volatility your friend because growth is your friend. Derivatives are like the mathematical function: they're not about the asset, they're about changes in the asset. Derivatives strip the base value, and focus on the change/volatility. Which makes volatility your enemy.
Derivatives are devilishly difficult to understand.
Also consider the monkey rule: Since the market rises more than it falls, even a monkey picking random investments should win most of the time. So a 77% loss rate is a huge red flag. Something isn't right with these products. It's common for brokers to design unnecessarily complex financial products which are internally rigged to make them a lot of money at your expense.
Any of those violate Harper's Rule: Never buy a financial product you don't understand.