Some anticipate that the bull is in effect, but the market still might go lower and see a further decline.
Is it ok to buy at extreme values and worth taking risk?
Investment most times is about risk. If you are ready to take the risk, then go ahead. Another thing i would like to say, is that you should take a reasonable risk, most especially that which you think if it falls, it will rise again, peradventure you intend going for long term.