2 questions about index funds:

1. Why do people bother investing in their own portfolios when they can just put it in an index fund?

Index funds have a return of 5-10% so called, and Warren Buffett himself said he would just put money into an index fund instead of trying to beat the market himself as it’s more efficient. I’m new to stocks, so am I missing something? I know theres a fee but it’s generally very small, especially when they do all the work for you.

1. I’m from the UK and we’re heading into a recession apparently, so should I put my savings into an index fund now or wait until the recession is coming to an end?

I know they say time in the market is better than timing the market, but i’d rather wait to put my savings in just after so that they don’t lose value before gaining value again.

I know i’m probably missing something so please don’t downvote, i’m just trying to learn. Thank you