I would say there are two theoretical advantages of pooling vs solo:
By example, assume you could get 12 ada solo as a lump, or 11.88 staking (I’ll assume 1% pool fee which is pretty standard in mining).
1 - Assuming that Ada appreciates throughout the year (maybe 1% month for a quick example, or 12% per year), you’d be better off to get 1 Ada per month that enjoys the monthly appreciation vs a lump 12 at random (i.e. could be very end of the year).
i.e. Month 1 = 1 Ada + 12 months at 1% appreciation = 1.12 Ada end of year
Month 2 = 1 Ada + 11 months at 1% appreciation = 1.11 Ada end of year
etc.
In other words the consistency of payout from a larger pool (the larger the better as it (ensures the most steady payouts for all members )) will almost certainly exceed the payout from solo assuming the currency itself is appreciating and you hold onto your rewards.
I used 12%, but imagine 50% or 100% appreciation and things look even more skewed for a pool.
2 - Because of the very low odds of being a slot leader doing solo, you better make sure you are 100% 24/7/365 running, ready and available with a fast connection b/c nothing would be more frustrating than waiting all year and the one time you are elected is when your computer reboots at night due to a ‘windows update’ or you don’t reply in the allocated X sec time b/c your computer was busy or similar. That would mean potentially waiting another year for another chance and of course losing that years reward vs the steady payout from pooling.
That said, we will all have to wait and see exactly how the staking will work,
what are the rewards, pool fees,etc. to truly compute the best option but the two points above are the general theoretical advantages over solo.