Most Africans especially Nigerians prefer liability to asset.
This is just an assumption, you can't speak for all Africans especially Nigerians, especially since you cannot tell all our preferences exactly. If you make this claim, you should have at least attached a source for your data.
Asset or liability?
The debate between what exactly we can call an Asset and Liability will continue for a while as I believe that some things that some people may consider as liabilities may be assets to other persons, it all depends on usage IMO. A car for instance which may be considered a liability to some, can be a asset to a business person who uses it to facilitate their business in form of logistics or transport services to bring profit, which is also in line of what an asset is.
I'm not saying buying expensive phones and cars isn't good but shouldn't be priority over ones investment. Phones and cars maintenance in some countries are expensive.
You spend majorly on maintenance and repairs when you buy a fairly used or not too good phone or car. If you can get a good one in very good working condition, it will be a while before you talk maintenance and repair, it would have served you already a lot and possibly made you some good returns already.