Will STI ever hit the $3700 mark again back in pre-2008 dip?

I have heard that in the long run, markets go up. But STI index seems very strange to me. It hit a high of 3700 just before 2008 crisis but even before the COVID dip, it only touched 3200. It seems to me that STI is trending down overall with each crisis.

How and why is this so? Isn't Singapore a safe place to invest in?

Will this ever change? I feel that millennials and younger generations are more into stocks than older generations. With demand, will this change still in a decade?