Holding is the only way for altcoin investors now unless you want to accept your losses and exit but its better to have patience, i have seen coins that worth 1,500$ a year ago and they are now 200$ , i have sold airdrop tokens that should worth 150$ for 10$ to sustain but i am not stupid enough to get rid of all my tokens and coins because market is not in my favour, be wise and remember that those tokens you are getting dispose off can turn something when market start turning for the better, be determined to win,when thinking forward always think backward as well.
You made a lot of good points but you failed to point out that holding is totally dependent on the type of coins in your portfolio; in as much as I will advice someone to hold I won't forget to caution the person to make sure he trusts the coins he is holding. When I say trust, am referring to use case etc. Also, most times, people sell not because they don't want to hold but maybe they have realised the market won't be favourable to them when they hold, instead they will sell and buy back later if deem possible. One thing, I know that is worth having aside knowledge is having a good strategy at all times. Dumping too early isn't a good idea always, although most times it might be worth it and also, holding when you are not sure of the coin isn't a good idea as well.