Yes and no. There is a bit of a hierarchy at work. In my opinion lights are a must after dark. But if somebody really can't be bothered to get lights then hi viz (or rather, the reflectives usually found on hi viz) may just help them avoid getting hit. And if they fail to have lights or hi viz, a helmet might prevent some harm should the worst happen. Might, I say. But I still prefer my lights in this hierarchy. Hence my bikes tend to look like a homage to Tron. Leaving as little as possible to chance.