$Esperion Therapeutics (ESPR.US)$ Why can't I suddenly buy it? What happened?

$Direxion Daily TSLA Bull 2X Shares (TSLL.US)$ Is this considered as stocks? Or etf, or something else? What are the differences between this and Tesla's common stock?
If the volatility follows Tesla's common stock, why don't people come here to buy due to its low cost, instead of buying Tesla's common stock?
I don't quite understand, for example, with the same $1000, the profit earned from buying this differs greatly compared to buying Tesla.
Is there any senior who can help me understand if there are any risks or management fees associated with this?

$Arm Holdings (ARM.US)$ Is now a good opportunity to buy the dip?

$Nikola (NKLA.US)$ Overall, this stock has been falling continuously. Is there still a future for this stock?

$Destiny Tech100 (DXYZ.US)$ The historical trend after April 9 once again occurred, wishing good luck to those who are trapped.

$ASML Holding (ASML.US)$ How come this trend is exactly the same as SMCI's trend?

$Destiny Tech100 (DXYZ.US)$ Why is the trading suspended?

$Super Micro Computer (SMCI.US)$ Will I lose all my money if it is delisted?
If not, will there be a chance for it to relist and rebound in the future, or will it be impossible forever?

$Super Micro Computer (SMCI.US)$ What should I do with an average price of 52? 😭😭
Previously bought at 890, thought it would rebound, kept buying during the fall, but it kept dropping.

$UnitedHealth (UNH.US)$ I don't understand why this stock is plummeting. Can someone explain?